chore(CI): Run tests on pushed commits

So that each commit in repo is tested, including merge commits that
aren't present in PRs. Also prepares for running releases only on push
but not on PRs.

Workflows have a global runs-on, so commit format check needs to be
split out from the shared PR and push workflow to since checking all
commit messages on pushes always fails due to very old commits not
following the proper format.

.github/workflows/commit-format.yaml

@@ -0,0 +1,14 @@
+name: Commit Format
+on: pull_request
+jobs:
+  verify-commit-format:
+    name: Verify Commit Format
+    runs-on: ubuntu-18.04
+    env:
+      GITHUB_CONTEXT: ${{ github.event.pull_request.commits_url }}
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0 # so that we can see the full commit range
+      - name: Run
+        run: ./.travis/verify-commit-format.sh

.github/workflows/test.yaml

@@ -1,17 +1,6 @@
-name: test
-on: pull_request
+name: Test
+on: [pull_request, push]
 jobs:
-  verify-commit-format:
-    name: Verify Commit Format
-    runs-on: ubuntu-18.04
-    env:
-      GITHUB_CONTEXT: ${{ github.event.pull_request.commits_url }}
-    steps:
-      - uses: actions/checkout@v2
-        with:
-          fetch-depth: 0 # so that we can see the full commit range
-      - name: Run
-        run: ./.travis/verify-commit-format.sh
   build-docs:
     name: Docs
     runs-on: ubuntu-18.04