Upgrade Error Prone fork 2.36.0-picnic-1 -> 2.36.0-picnic-2 (#1499)

This new release is published using GitHub Packages rather than
JitPack. This comes with a simpler release setup and a (hopefully) more
stable package repository. A minor downside is that GitHub Packages
require authenticated access, even for read access. The documentation
has been updated accordingly.

The new release is no longer published using a custom groupId, enabling
some build simplifications.

While there, some obsolete fork-related documentation and configuration
is dropped.

See:
- https://github.com/PicnicSupermarket/error-prone/releases/tag/v2.36.0-picnic-2
- https://github.com/PicnicSupermarket/error-prone/compare/v2.36.0-picnic-1...v2.36.0-picnic-2

.github/workflows/build.yml

@@ -33,7 +33,9 @@ jobs:
           allowed-endpoints: >
             api.adoptium.net:443
             github.com:443
+            github-registry-files.githubusercontent.com:443
             jitpack.io:443
+            maven.pkg.github.com:443
             objects.githubusercontent.com:443
             repo.maven.apache.org:443
       # We run the build twice for each supported JDK: once against the
@@ -53,6 +55,8 @@ jobs:
         run: mvn -T1C install javadoc:jar
       - name: Build project with self-check against Error Prone fork
         run: mvn -T1C clean verify -Perror-prone-fork -Pnon-maven-central -Pself-check -s settings.xml
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       - name: Remove installed project artifacts
         run: mvn dependency:purge-local-repository -DmanualInclude='${project.groupId}' -DresolutionFuzziness=groupId
 

.github/workflows/deploy-website.yml

@@ -21,6 +21,7 @@ jobs:
             api.github.com:443
             bestpractices.coreinfrastructure.org:443
             blog.picnic.nl:443
+            docs.github.com:443
             errorprone.info:443
             github.com:443
             img.shields.io:443