Need to use `jetpack_offline_mode` for JetPack >= 8.8.0

For no apparent reason, Automattic have renamed the filter from jetpack_development_mode to jetpack_offline_mode. There is no actual change in how it works or the hook function signature.

They have retained the jetpack_development_mode filter for now, but with a deprecation notice.

Thus this plugin needs updating to test the JetPack version and if it is >= 8.8.0 use the jetpack_offline_mode filter instead of jetpack_development_mode.

Otherwise, the error log gets filled up with several deprecation notices per request.

• This topic was modified 3 years, 4 months ago by jqz. Reason: typo