chore: update checkout action to v3 in README to avoid NodeJS 12 warning

Author: madamak

README.md

@@ -50,7 +50,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Create temp dbt profiles
         run: "printf %s \"$DBT_PROFILES\" > ./profiles.yml"
         env: