Update README.md to reference v4 version of actions examples

Author: peter-murray

README.md

@@ -91,7 +91,7 @@ jobs:
     steps:
       - name: Get Token
         id: get_workflow_token
-        uses: peter-murray/workflow-application-token-action@v3
+        uses: peter-murray/workflow-application-token-action@v4
         with:
           application_id: ${{ secrets.APPLICATION_ID }}
           application_private_key: ${{ secrets.APPLICATION_PRIVATE_KEY }}
@@ -114,7 +114,7 @@ jobs:
     steps:
       - name: Get Token
         id: get_workflow_token
-        uses: peter-murray/workflow-application-token-action@v3
+        uses: peter-murray/workflow-application-token-action@v4
         with:
           application_id: ${{ secrets.APPLICATION_ID }}
           application_private_key: ${{ secrets.APPLICATION_PRIVATE_KEY }}
@@ -138,7 +138,7 @@ jobs:
     steps:
       - name: Get Token
         id: get_workflow_token
-        uses: peter-murray/workflow-application-token-action@v3
+        uses: peter-murray/workflow-application-token-action@v4
         with:
           application_id: ${{ secrets.APPLICATION_ID }}
           application_private_key: ${{ secrets.APPLICATION_PRIVATE_KEY }}
@@ -167,7 +167,7 @@ jobs:
     steps:
       - name: Get Token
         id: get_workflow_token
-        uses: peter-murray/workflow-application-token-action@v3
+        uses: peter-murray/workflow-application-token-action@v4
         with:
           application_id: ${{ secrets.APPLICATION_ID }}
           application_private_key: ${{ secrets.APPLICATION_PRIVATE_KEY }}