Use stable go version in pull request tests.

Author: robdimsdale

.github/workflows/test-pull-request.yml

@@ -14,7 +14,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v1
         with:
-          go-version: 1.19.x
+          go-version: stable
 
       - name: Checkout
         uses: actions/checkout@v2
@@ -53,7 +53,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v1
         with:
-          go-version: 1.19.x
+          go-version: stable
 
       - name: Checkout
         uses: actions/checkout@v2