Update of the actions/checkout to v3 (softprops#287)

Hi,
Thanks for such a helpful tool. I want to suggest updating the version of `actions/checkout@v2` to `actions/checkout@v3` since GitHub is moving away from node12 to node16 (https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/).

Cheers!

README.md

@@ -41,7 +41,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Release
         uses: softprops/action-gh-release@v1
         if: startsWith(github.ref, 'refs/tags/')
@@ -62,7 +62,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Release
         uses: softprops/action-gh-release@v1
 ```
@@ -88,7 +88,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Build
         run: echo ${{ github.sha }} > Release.txt
       - name: Test
@@ -112,7 +112,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Build
         run: echo ${{ github.sha }} > Release.txt
       - name: Test
@@ -144,7 +144,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Generate Changelog
         run: echo "# Good things have arrived" > ${{ github.workspace }}-CHANGELOG.txt
       - name: Release