Use public GitHub runners

Author: andyw8

.github/workflows/ci.yml

@@ -5,7 +5,7 @@ on: [push, pull_request]
 
 jobs:
   test:
-    runs-on: shopify-ubuntu-latest
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
       - name: Set up Ruby
@@ -21,4 +21,4 @@ jobs:
         run: bin/rubocop
 
       - name: Run tests
-        run: bundle exec rake
+        run: bundle exec rake

.github/workflows/cla.yml

@@ -9,7 +9,7 @@ on:
 
 jobs:
   cla:
-    runs-on: shopify-ubuntu-latest
+    runs-on: ubuntu-latest
     if: |
       (github.event.issue.pull_request
         && !github.event.issue.pull_request.merged_at

.github/workflows/dependabot_automerge.yml

@@ -7,7 +7,7 @@ permissions:
 
 jobs:
   dependabot:
-    runs-on: shopify-ubuntu-latest
+    runs-on: ubuntu-latest
     if: ${{ github.actor == 'dependabot[bot]' }}
     steps:
       - name: Dependabot metadata

.github/workflows/release.yml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   publish:
-    runs-on: shopify-ubuntu-latest
+    runs-on: ubuntu-latest
 
     steps:
       - uses: actions/checkout@v3