update actions/checkout@v3 to v4

[skateball]

Hi,
you may want to update this to v4

java-buildpack/.github/workflows/release-reminder.yml

Line 55 in 1c46ab6

uses: actions/checkout@v3

Regards Christian

[ramonskie]

the buildpack has been rewritten in go with libbuildpack.

please reopen if the issue is still relevant