use new default branch

.github/workflows/postgres-service.yml

@@ -3,16 +3,16 @@ name: Postgres Service Example
 on:
   push:
     branches:
-    - master
+    - main
   pull_request:
     branches:
-    - master
+    - main
 
 jobs:
   container-job:
     runs-on: ubuntu-latest
-    
-    # runs all of the steps inside the specified container rather than on the VM host.  
+
+    # runs all of the steps inside the specified container rather than on the VM host.
     # Because of this the network configuration changes from host based network to a container network.
     container:
       image:  node:10.16-jessie
@@ -30,7 +30,7 @@ jobs:
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
 
     steps:
-    - uses: actions/checkout@v1     
+    - uses: actions/checkout@v1
     - run: npm ci
       working-directory: ./postgres
     - run: node client.js
@@ -60,7 +60,7 @@ jobs:
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
 
     steps:
-    - uses: actions/checkout@v1     
+    - uses: actions/checkout@v1
     - run: npm ci
       working-directory: ./postgres
     - run: node client.js