Update to rules_jvm_external 6.2, repin maven deps

[mbland]

Details:

• https://github.com/bazelbuild/rules_jvm_external/releases/tag/6.2

This new version resolves the issue mentioned in #182:

• https://github.com/bazelbuild/rules_jvm_external/issues/1189

Fixed by:

• https://github.com/bazelbuild/rules_jvm_external/pull/1122

Per my comment on that issue, source JARs are no longer fetched without explicitly setting fetch_sources = True. This is why they no longer appear in maven_install.json.

Finally, @shs96c noted to me in private that:

...with recent rules_jvm_external releases, all you need to update is bazel run @maven//:pin. There’s no need for the unpinned_maven repo any more.

I removed the unpinned_maven repo and ran REPIN=1 bazel run @maven//:pin to regenerate maven_install.json. This also removed the unpinned_maven entries from MODULE.bazel.lock.

I'll update this section of my Bzlmod migration blog post after merging this change:

• https://blog.engflow.com/2024/06/27/migrating-to-bazel-modules-aka-bzlmod---the-easy-parts/#with-rules_jvm_external