The process '/opt/hostedtoolcache/opam/2.1.5/x86_64/opam' failed with exit code 20

The operation was canceled.

An error has been caught in some system package index files, so the system package index files have been re-synchronised, and the system package installation has been retried: the process '/opt/hostedtoolcache/opam/2.1.5/x86_64/opam' failed with exit code 20

The following actions uses node12 which is deprecated and will be forced to run on node16: actions/checkout@v2. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/