fix shell placement

Author: cycleapple

action.yml

@@ -8,19 +8,20 @@ inputs:
 
 runs:
   using: 'composite'
-  shell: bash
   steps:
     - name: Checkout
       uses: actions/checkout@v2
 
     - uses: fregante/setup-git-user@v2
 
     - name: Fetch branches and update working directory
+      shell: bash
       run: |
         git fetch origin ${{ github.event.pull_request.head.ref }}
         git fetch origin ${{ github.event.pull_request.base.ref }}
 
     - name: Check if branches are up to date
+      shell: bash
       id: checkBranches
       run: |
         git checkout ${{ github.event.pull_request.head.ref }}
@@ -34,6 +35,7 @@ runs:
         fi
 
     - name: Merge base branch into PR branch
+      shell: bash
       if: steps.checkBranches.outputs.mergeRequired == 'true'
       run: |
         git merge --no-edit --no-commit origin/${{ github.event.pull_request.base.ref }}
@@ -44,6 +46,7 @@ runs:
         git commit -m "Merge ${{ github.event.pull_request.base.ref }} into ${{ github.event.pull_request.head.ref }}"
 
     - name: Push changes
+      shell: bash
       if: steps.checkBranches.outputs.mergeRequired == 'true'
       run: |
         git push origin ${{ github.event.pull_request.head.ref }}