Fix main-into-next-pr workflow

Need an update to create-pull-request@v6 to fix [an issue with the GitHub API](peter-evans/create-pull-request#2790).

.github/workflows/main-into-next-pr.yml

@@ -9,7 +9,7 @@ jobs:
         runs-on: ubuntu-latest
         steps:
             - name: Checkout code
-              uses: actions/checkout@v3
+              uses: actions/checkout@v4
               with:
                   fetch-depth: 0 # Needed to also fetch next branch
 
@@ -36,7 +36,7 @@ jobs:
                   echo 'PR_BODY=This is an automated pull request to merge changes from `main` into `next`. It has merge conflicts. To resolve conflicts, check out the branch `merge-main-into-next` locally, make any necessary changes to conflicting files, and commit and publish your changes.' >> $GITHUB_ENV
 
             - name: Create pull request
-              uses: peter-evans/create-pull-request@v5
+              uses: peter-evans/create-pull-request@v6
               with:
                   token: ${{ secrets.GITHUB_TOKEN }}
                   title: ${{ env.PR_TITLE }}