dev-cmd/contributions: Special Homebrew-specific quarter dates

- These aren't standard quarterly dates. We've chosen our own so that we
  can use September to December's maintainer activity stats as part of
  checking eligibility for expensed attendance at the AGM in February
  each year.

Author: issyl0

Library/Homebrew/dev-cmd/contributions.rb

@@ -282,12 +282,16 @@ def total(results)
 
       sig { returns(T::Hash[Integer, T::Array[String]]) }
       def quarter_dates
+        # These aren't standard quarterly dates. We've chosen our own so that we
+        # can use recent maintainer activity stats as part of checking
+        # eligibility for expensed attendance at the AGM in February each year.
         current_year = Date.today.year
+        last_year = current_year - 1
         {
-          1 => [Date.new(current_year, 1, 1).iso8601, Date.new(current_year, 3, 31).iso8601],
-          2 => [Date.new(current_year, 4, 1).iso8601, Date.new(current_year, 6, 30).iso8601],
-          3 => [Date.new(current_year, 7, 1).iso8601, Date.new(current_year, 9, 30).iso8601],
-          4 => [Date.new(current_year, 10, 1).iso8601, Date.new(current_year, 12, 31).iso8601],
+          1 => [Date.new(last_year, 9, 1).iso8601, Date.new(last_year, 12, 1).iso8601],
+          2 => [Date.new(last_year, 12, 1).iso8601, Date.new(current_year, 3, 1).iso8601],
+          3 => [Date.new(current_year, 3, 1).iso8601, Date.new(current_year, 6, 1).iso8601],
+          4 => [Date.new(current_year, 6, 1).iso8601, Date.new(current_year, 9, 1).iso8601],
         }
       end
     end