fix and modernize GitHub Actions config

Author: SethTisue

.github/workflows/ci.yml

@@ -2,20 +2,20 @@ name: test
 on:
   push:
     branches:
-      - main
+      - 2.13.x
   pull_request:
 jobs:
   test:
     strategy:
       fail-fast: false
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - uses: coursier/cache-action@v6
-    - uses: actions/setup-java@v2
+    - uses: actions/setup-java@v3
       with:
         distribution: temurin
         java-version: 8
     - name: Test
       # This runs the template with the default parameters, and runs test within the templated app.
-      run: sbt -Dfile.encoding=UTF8 -J-XX:ReservedCodeCacheSize=256M test
+      run: sbt -Dfile.encoding=UTF8 test