upgrade Checkout GitHub action (#317)

Author: jmckenna

.github/workflows/build-linux.yml

@@ -11,7 +11,7 @@ jobs:
       runs-on: ${{ matrix.os }}
       steps:
         - name: Checkout repository
-          uses: actions/checkout@v2
+          uses: actions/checkout@v3
 
         - name: Install dependencies
           run: |

.github/workflows/build-windows.yml

@@ -11,7 +11,7 @@ jobs:
       runs-on: ${{matrix.os}}
       steps:
         - name: Checkout repository
-          uses: actions/checkout@v2
+          uses: actions/checkout@v3
 
         - name: Install dependencies
           run: |