feat: increase difficulty to 40m hash

[hunjixin]

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1. increase difficulty to 40m hash
2. give 6 more block to confirm challenge

this difficulty was calculate with this tool https://github.com/hunjixin/pow-tool/tree/main/difficulty
// Theoretically A machine with a hash rate of 40M has a probability of no more than 0.00001 of not finding a nonce that meets the difficulty within 36 blocks.

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Task/Issue reference

Closes: https://github.com/Lilypad-Tech/internal/issues/205

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[AquiGorka]

@hunjixin why do we need this?

@richardbremner and @alvin-reyes if we do need this, we need a plan to deploy the implementation contract asap

[hunjixin]

@hunjixin why do we need this?

@richardbremner and @alvin-reyes if we do need this, we need a plan to deploy the implementation contract asap

its useful before. because performance improve much gpu will finish very quickly. but i am not sure its needed in current.
if keep using keccak. need a more hard difficulty.

[AquiGorka]

It does not feel then that we need this, and since we are moving towards a different approach with pow maybe not worth the extra effort right now to deploy the change.

[richardbremner]

I'll close this, we don't want to invest more effort in the old pow mechanism

[hunjixin]

https://github.com/Lilypad-Tech/internal/issues/205

[hunjixin]

this is different time and corresponding hashrate range for 8m (current use)

12s     min: 222.2222202                max: 181.8181801
24s     min: 111.1111101                max: 90.90909003
36s     min: 74.07407339                max: 60.60606002
48s     min: 55.55555504                max: 45.45454501
60s     min: 44.44444403                max: 36.36363601
72s     min: 37.0370367         max: 30.30303001
84s     min: 31.74603145                max: 25.97402572
96s     min: 27.77777752                max: 22.72727251
108s    min: 24.6913578         max: 20.20202001
120s    min: 22.22222202                max: 18.18181801
132s    min: 20.20202002                max: 16.52892546
144s    min: 18.51851835                max: 15.151515
156s    min: 17.09401694                max: 13.98601385
168s    min: 15.87301573                max: 12.98701286
180s    min: 14.81481468                max: 12.121212
192s    min: 13.88888876                max: 11.36363625
204s    min: 13.0718953         max: 10.69518706
216s    min: 12.3456789         max: 10.10101
228s    min: 11.69590632                max: 9.569377898
240s    min: 11.11111101                max: 9.090909003
252s    min: 10.58201048                max: 8.658008574
264s    min: 10.10101001                max: 8.26446273
276s    min: 9.66183566         max: 7.905138263
288s    min: 9.259259174                max: 7.575757502
300s    min: 8.888888807                max: 7.272727202
312s    min: 8.547008468                max: 6.993006925
324s    min: 8.230452599                max: 6.734006669
336s    min: 7.936507863                max: 6.493506431
348s    min: 7.662835178                max: 6.269592416
360s    min: 7.407407339                max: 6.060606002

this is different time and corresponding hashrate range for 40m (this pr )

// this means if miner submit proof within 12s, his hashrates was between 1090.909133 ~ 1333.333385. 
12s     min: 1333.333385                max: 1090.909133   
24s     min: 666.6666926                max: 545.4545666
36s     min: 444.4444617                max: 363.6363777
48s     min: 333.3333463                max: 272.7272833
60s     min: 266.666677         max: 218.1818266
72s     min: 222.2222309                max: 181.8181889
84s     min: 190.4761979                max: 155.8441619
96s     min: 166.6666731                max: 136.3636417
108s    min: 148.1481539                max: 121.2121259
120s    min: 133.3333385                max: 109.0909133
132s    min: 121.2121259                max: 99.17355757
144s    min: 111.1111154                max: 90.90909444
156s    min: 102.5641065                max: 83.91608717
168s    min: 95.23809894                max: 77.92208095
180s    min: 88.88889234                max: 72.72727555
192s    min: 83.33333657                max: 68.18182083
204s    min: 78.4313756         max: 64.17112548
216s    min: 74.07407695                max: 60.60606296
228s    min: 70.17544132                max: 57.41627017
240s    min: 66.66666926                max: 54.54545666
252s    min: 63.49206596                max: 51.94805396
264s    min: 60.60606296                max: 49.58677878
276s    min: 57.97101675                max: 47.43083188
288s    min: 55.55555771                max: 45.45454722
300s    min: 53.33333541                max: 43.63636533
312s    min: 51.28205327                max: 41.95804359
324s    min: 49.38271797                max: 40.40404197
336s    min: 47.61904947                max: 38.96104047
348s    min: 45.97701328                max: 37.61755632
360s    min: 44.44444617                max: 36.36363777