Revert hashicorp/setup-terraform action to v2 due to failure

Author: markgoddard

.github/workflows/stackhpc-all-in-one.yml

@@ -106,7 +106,7 @@ jobs:
           fi
 
       - name: Install terraform
-        uses: hashicorp/setup-terraform@v3
+        uses: hashicorp/setup-terraform@v2
 
       - name: Initialise terraform
         run: terraform init