Update CI to cancel previous runs and to use v2 of setup-java.

RELNOTES=n/a
PiperOrigin-RevId: 367070554
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index dbd1514..23ef28c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,6 +16,11 @@
         java: [ 8, 11 ]
     runs-on: ubuntu-latest
     steps:
+      # Cancel any previous runs for the same branch that are still running.
+      - name: 'Cancel previous runs'
+        uses: styfle/cancel-workflow-action@0.8.0
+        with:
+          access_token: ${{ github.token }}
       - name: 'Check out repository'
         uses: actions/checkout@v2
       - name: 'Cache local Maven repository'
@@ -26,9 +31,10 @@
           restore-keys: |
             maven-
       - name: 'Set up JDK ${{ matrix.java }}'
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
           java-version: ${{ matrix.java }}
+          distribution: 'zulu'
       - name: 'Install'
         shell: bash
         run: mvn -B dependency:go-offline test clean -U --quiet --fail-never -DskipTests=true -f build-pom.xml
@@ -52,9 +58,10 @@
           restore-keys: |
             maven-
       - name: 'Set up JDK 11'
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
           java-version: 11
+          distribution: 'zulu'
           server-id: sonatype-nexus-snapshots
           server-username: CI_DEPLOY_USERNAME
           server-password: CI_DEPLOY_PASSWORD
@@ -80,9 +87,10 @@
           restore-keys: |
             maven-
       - name: 'Set up JDK 11'
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
           java-version: 11
+          distribution: 'zulu'
       - name: 'Generate latest docs'
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}