make sure boolean filters work with implicit strings

spec/active_interaction/filters/boolean_filter_spec.rb

@@ -11,6 +11,20 @@
           expect(filter.cast(value, nil)).to be_falsey
         end
       end
+
+      context 'with an implicit string' do
+        let(:value) do
+          Class.new do
+            def to_str
+              'false'
+            end
+          end.new
+        end
+
+        it 'returns false' do
+          expect(filter.cast(value, nil)).to be_falsey
+        end
+      end
     end
 
     context 'truthy' do
@@ -19,6 +33,20 @@
           expect(filter.cast(value, nil)).to be_truthy
         end
       end
+
+      context 'with an implicit string' do
+        let(:value) do
+          Class.new do
+            def to_str
+              'true'
+            end
+          end.new
+        end
+
+        it 'returns true' do
+          expect(filter.cast(value, nil)).to be_truthy
+        end
+      end
     end
   end