Update peter-evans/create-pull-request action to v8

Author: renovate[bot]

.github/workflows/up.yml

@@ -16,7 +16,7 @@ jobs:
           latest=$(git tag --sort=creatordate | tail -1) && \
           sed -E -i "s/<version>[^<]+/<version>${latest}/g" README.md && \
           sed -E -i "s/org.cactoos:cactoos:.+/org.cactoos:cactoos::${latest}/g" README.md
-      - uses: peter-evans/create-pull-request@v7
+      - uses: peter-evans/create-pull-request@v8
         with:
           sign-commits: true
           commit-message: 'new version in README'