Add Xcode 11.4 object version.

[dnkoutso]

closes #744

[amorde]

What changed in the project format? Fine merging this but the version wouldn't bump without something changing right?

[dnkoutso]

Who knows? Apple bumps that number when they do...it seems from the issue report that Xcode 11.4 has a new version of 53.

[amorde]

I was under the impression it only gets bumped if something actually changes (ex. new attribute gets added)

this same topic came up last time #687 (comment)

[dnkoutso]

Inteeeeresting....you are correct. I guess this doesnt matter since after we added this we are now more strict and crash for an unknown object version. This PR would fix the crash and we should get warnings for new attributes?

[amorde]

Don't we also crash on unknown attributes?

[dnkoutso]

No we warn for these.

[dnkoutso]

It actually says to file an issue in the warning.

[amorde]

Ah I see

Xcodeproj/spec/project/object_spec.rb

Lines 160 to 167 in 80a2cda

	it 'warns if it encounters an unknown attribute in a plist' do
	UI.expects(:warn).with "[!] Xcodeproj doesn't know about the following " \
	"attributes {\"unknown_attribute\"=>\"might be a reference\"} for the 'PBXFileReference' isa." \
	"\nIf this attribute was generated by Xcode please file " \
	'an issue: https://github.com/CocoaPods/Xcodeproj/issues/new'
	@objects_by_uuid_plist[@object.uuid]['unknown_attribute'] = 'might be a reference'
	@object.configure_with_plist(@objects_by_uuid_plist)
	end

Would still prefer to actually add support for whatever changed but understand the need to fix crashes sooner rather than later