[jdk17] RFR: 8269148: Update minor GCC version in GitHub Actions pipeline

[Aleksey Shipilev]

It seems Ubuntu had bumped the version for GCC, so GHA started to fail with e.g.:


The following packages have unmet dependencies:
 g++-10-s390x-linux-gnu : Depends: gcc-10-s390x-linux-gnu-base (= 10.2.0-5ubuntu1~20.04cross1) but 10.3.0-1ubuntu1~20.04cross1 is to be installed
 gcc-10-s390x-linux-gnu : Depends: cpp-10-s390x-linux-gnu (= 10.2.0-5ubuntu1~20.04cross1) but 10.3.0-1ubuntu1~20.04cross1 is to be installed
                          Depends: gcc-10-s390x-linux-gnu-base (= 10.2.0-5ubuntu1~20.04cross1) but 10.3.0-1ubuntu1~20.04cross1 is to be installed
E: Unable to correct problems, you have held broken packages.
Error: Process completed with exit code 100.


I believe we should just update to `10.3.0-1ubuntu1~20.04`.

Additional testing:
 - [x] GitHub Actions, package installation steps work
 - [ ] GitHub Actions, the builds complete

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Commit messages:
 - 8269148: GitHub actions should use updated minor GCC version

Changes: https://git.openjdk.java.net/jdk17/pull/120/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=120&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269148
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/120.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/120/head:pull/120

PR: https://git.openjdk.java.net/jdk17/pull/120