Update sqlite3 requirement from ~> 1.6 to ~> 2.6

Updates the requirements on [sqlite3](https://github.com/sparklemotion/sqlite3-ruby) to permit the latest version.
- [Release notes](https://github.com/sparklemotion/sqlite3-ruby/releases)
- [Changelog](https://github.com/sparklemotion/sqlite3-ruby/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/sqlite3-ruby@v1.6.0...v2.6.0)

---
updated-dependencies:
- dependency-name: sqlite3
  dependency-version: 2.6.0
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

publify_core.gemspec

@@ -66,7 +66,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rubocop-rspec", "~> 2.25.0"
   s.add_development_dependency "shoulda-matchers", "~> 6.0"
   s.add_development_dependency "simplecov", "~> 0.22.0"
-  s.add_development_dependency "sqlite3", "~> 1.6"
+  s.add_development_dependency "sqlite3", "~> 2.6"
   s.add_development_dependency "timecop", "~> 0.9.1"
   s.add_development_dependency "webmock", "~> 3.3"
   s.metadata["rubygems_mfa_required"] = "true"