copy-workflow fails if repo uses submodules

[galargh]

https://github.com/filecoin-project/go-commp-utils uses https://github.com/filecoin-project/filecoin-ffi as a submodule. The latter defines go1.13 in it's go.mod file. When we try to copy workflows for go-commp-utils, we also try to update go version in the submodule which fails: https://github.com/protocol/.github/runs/4485167112?check_suite_focus=true

We could temporarily fix it by adding filecoin-ffi to unified CI framework (which we should) but it won't stop the issue from reappearing during go upgrades for example.

[marten-seemann]

I think @mvdan had some thoughts about this, but I think that was somewhere on Slack and not on an issue here.

[mvdan]

The way many modules require filecoin-ffi today is quite broken; see filecoin-project/filecoin-ffi#209. This is what leads to the git submodule and the replace directive, and the manual steps required to build the parent Go module.

I think we should focus on making filecoin-ffi easy to use as a Go module (see the link above), rather than adding ways to work around the problems it causes today :)

[galargh]

The initial issue - updating go.mod in submodules - has been resolved by updating only those go.mod files that are committed - ipdxco/unified-github-workflows@ddcf7dc.