Update version to 0.5.1 in iss

[ci skip]

Author: gaborcsardi

rig.iss

@@ -2,7 +2,7 @@
 ; SEE THE DOCUMENTATION FOR DETAILS ON CREATING INNO SETUP SCRIPT FILES!
 
 #define MyAppName "rig -- The R Installation Manager"
-#define MyAppVersion "0.5.0"
+#define MyAppVersion "0.5.1"
 #define MyAppPublisher "Gabor Csardi"
 #define MyAppURL "https://github.com/r-lib/rig"
 #define MyAppExeName "rig.exe"