Pin minitest to < 6 to fix missing minitest/mock (#154)

* Pin minitest to < 6 to fix missing minitest/mock

Minitest 6.0 moved mock.rb to a separate minitest-mock gem,
breaking `require "minitest/mock"` in tests. Pin to < 6 to
retain the built-in mock support.

* Fix indentation in chunky_png_driver.rb to pass Standard Ruby linter

---------

Co-authored-by: Twill <agent@twill.ai>

Author: twill-hq[bot]

gems.rb

@@ -15,7 +15,7 @@
 group :test do
   gem "capybara", ">= 3.26"
   gem "mutex_m" # Needed for RubyMine debugging.  Try removing it.
-  gem "minitest", require: false
+  gem "minitest", "< 6", require: false
   gem "minitest-stub-const", require: false
   gem "simplecov", require: false
   gem "rspec", require: false

lib/capybara/screenshot/diff/drivers/chunky_png_driver.rb

@@ -254,10 +254,10 @@ def shift_distance_at(new_img, old_img, x, y, color_distance_limit:)
                   if (x - shift_distance) >= 0 # left
                     ([0, top_row + 1].max..[y + shift_distance, new_img.height - 2].min)
                       .each do |dy|
-                      if color_matches(new_img, org_color, x - shift_distance, dy, color_distance_limit)
-                        return shift_distance
+                        if color_matches(new_img, org_color, x - shift_distance, dy, color_distance_limit)
+                          return shift_distance
+                        end
                       end
-                    end
                   else
                     bounds_breached += 1
                   end
@@ -273,10 +273,10 @@ def shift_distance_at(new_img, old_img, x, y, color_distance_limit:)
                   if (x + shift_distance) < new_img.width # right
                     ([0, top_row + 1].max..[y + shift_distance, new_img.height - 2].min)
                       .each do |dy|
-                      if color_matches(new_img, org_color, x + shift_distance, dy, color_distance_limit)
-                        return shift_distance
+                        if color_matches(new_img, org_color, x + shift_distance, dy, color_distance_limit)
+                          return shift_distance
+                        end
                       end
-                    end
                   else
                     bounds_breached += 1
                   end