Fix removing attachments with boolean values on Ruby 3.2

Passing boolean values to the remove attachment attribute accidentally
worked due to Object#=~ being defined. However, that is removed in Ruby
3.2, so we make the implementation explicitly work for boolean values.

Closes #620

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## HEAD
 
+* `remove_attachment` – Fix passing boolean values being broken in Ruby 3.2 (@janko)
+
 * `model` – When duplicating a record, make the duplicated attacher reference the duplicated record (@janko)
 
 ## 3.4.0 (2021-06-14)

lib/shrine/plugins/remove_attachment.rb

@@ -39,6 +39,8 @@ def change?(file)
 
         # Rails sends "0" or "false" if the checkbox hasn't been ticked.
         def remove?
+          return remove if [true, false].include?(remove)
+
           remove && remove != "" && remove !~ /\A(0|false)\z/
         end
       end

test/plugin/remove_attachment_test.rb

@@ -62,6 +62,14 @@
         assert @attacher.changed?
       end
 
+      it "deassigns the attached file on true" do
+        @attacher.file = @attacher.upload(fakeio)
+        @attacher.remove = true
+
+        assert_nil @attacher.file
+        assert @attacher.changed?
+      end
+
       it "keeps the file on falsy value" do
         @attacher.file = @attacher.upload(fakeio)
 
@@ -73,6 +81,9 @@
 
         @attacher.remove = "false"
         refute_nil @attacher.file
+
+        @attacher.remove = false
+        refute_nil @attacher.file
       end
     end