Update github action after default branch update (open-telemetry#26)

.github/workflows/lint-test.yaml

@@ -1,29 +1,45 @@
 name: Lint and Test Charts
 
-on: pull_request
-
+on:
+  pull_request:
+    branches:
+      - main
 jobs:
   lint-test:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
 
-      - name: Fetch history
-        run: git fetch --prune --unshallow
+      - name: Set up Helm
+        uses: azure/setup-helm@v1
+        with:
+          version: v3.4.0
 
-      - name: Run chart-testing (lint)
-        id: lint
-        uses: helm/chart-testing-action@v1.0.0
+      - uses: actions/setup-python@v2
         with:
-          command: lint
+          python-version: 3.7
+
+      - name: Set up chart-testing
+        uses: helm/chart-testing-action@v2.0.1
+
+      - name: Run chart-testing (list-changed)
+        id: list-changed
+        run: |
+          changed=$(ct list-changed --target-branch main)
+          if [[ -n "$changed" ]]; then
+            echo "::set-output name=changed::true"
+          fi
+
+      - name: Run chart-testing (lint)
+        run: ct lint --target-branch main
 
       - name: Create kind cluster
         uses: helm/kind-action@v1.0.0
         # Only build a kind cluster if there are chart changes to test.
         if: steps.lint.outputs.changed == 'true'
 
       - name: Run chart-testing (install)
-        uses: helm/chart-testing-action@v1.0.0
-        with:
-          command: install
+        run: ct install --target-branch main

.github/workflows/release.yaml

@@ -3,7 +3,7 @@ name: Release Charts
 on:
   push:
     branches:
-      - master
+      - main
 
 jobs:
   release: