RFR: JDK-8301097: Update GHA XCode to 12.5.1

Wed Jan 25 16:28:27 UTC 2023

We are using 11.7 for x86 and 12.4 for aarch64. We should probably be using the same version for both. I assume aarch64 is using a more recent one for better aarch64 support in XCode. 12.4 is not the last release in the 12.x series, that would be 12.5.1, so we should update both to use that.

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Commit messages:
 - Update GHA XCode to 12.5.1

Changes: https://git.openjdk.org/jdk/pull/12203/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12203&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8301097
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/12203.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12203/head:pull/12203

PR: https://git.openjdk.org/jdk/pull/12203