add github actions for push event

Author: ishanrai05

.github/workflows/check_shell_script_on_push.yml

@@ -0,0 +1,25 @@
+name: ShellCheck/push
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2.2.0
+    - name: Get Diff Action
+      uses: technote-space/get-diff-action@v1.2.8
+      with:
+        SUFFIX_FILTER: .sh
+    - name: Install ShellCheck
+      run: |
+        sudo apt-get install shellcheck
+      if: env.GIT_DIFF
+    - name: Lint with ShellCheck
+      run: |
+        shellcheck --shell=bash -x ${{ env.GIT_DIFF }}
+      if: env.GIT_DIFF