The version now comes from the git tag, so a build can't disagree with its release

Builds after a tag name themselves after it plus the commits since, and the version code is
worked out from the numbers instead of set by hand.

.github/workflows/release.yml

@@ -12,6 +12,9 @@ jobs:
       contents: write
     steps:
       - uses: actions/checkout@v4
+        with:
+          # The build names itself after the newest tag, which a shallow clone doesn't have.
+          fetch-depth: 0
 
       - uses: actions/setup-java@v4
         with: