Add a way to detect the newly introduced (1.21.9) pack version format

[MelanX]

Here you can see that the 1.21.9 version changed it's pack version format:

Without this PR, this issue occurs:

Caused by: java.lang.RuntimeException: Could not get pack versions for 1.21.9
	at org.moddingx.modgradle.util.ModGradleVersionAccess.packVersions(ModGradleVersionAccess.java:116)
	at org.moddingx.modgradle.util.ModGradleVersionAccess.resource(ModGradleVersionAccess.java:82)
	at org.moddingx.modgradle.plugins.meta.setup.ModContext.<init>(ModContext.java:46)
	at org.moddingx.modgradle.plugins.meta.setup.ModBuildSetup.configureBuild(ModBuildSetup.java:19)
	at org.moddingx.modgradle.plugins.meta.ModExtension.configure(ModExtension.java:37)
	... 195 more
Caused by: java.io.IOException: No valid version.json file found in client.
	at org.moddingx.modgradle.util.ModGradleVersionAccess.packVersions(ModGradleVersionAccess.java:110)
	... 199 more

This PR fixes that.