Update brew before updating formula

Before create a PR to homebrew/homebrew-core we need to be sure that
local instance of homebre/homebrew-core is up-to-date otherwise it could
create merge conflicts.

See Homebrew/homebrew-core#61260 (comment)
See Homebrew/homebrew-core#61823

Author: bayandin

.github/workflows/release-packages.yaml

@@ -53,6 +53,7 @@ jobs:
         run: echo "::set-env name=RELEASE_TAG::${GITHUB_REF/refs\/tags\/}"
       - name: Create homebrew PR
         run: |
+          brew update-reset
           brew bump-formula-pr --tag "$RELEASE_TAG" --revision "$GITHUB_SHA" cbmc
         env:
           HOMEBREW_GITHUB_API_TOKEN: ${{ secrets.DB_CI_CPROVER_ACCESS_TOKEN }}