chore: add standard devenv.nix #5

...mod/cache/download/sumdb/sum.golang.org/tile/8/2/001.p/43

.../mod/cache/download/sumdb/sum.golang.org/tile/8/3/000.p/1

.devenv/state/go/pkg/mod/cache/lock

...e/go/pkg/mod/github.com/davecgh/go-spew@v1.1.1/.gitignore

.../go/pkg/mod/github.com/davecgh/go-spew@v1.1.1/.travis.yml

...tate/go/pkg/mod/github.com/davecgh/go-spew@v1.1.1/LICENSE

...te/go/pkg/mod/github.com/davecgh/go-spew@v1.1.1/README.md

...o/pkg/mod/github.com/davecgh/go-spew@v1.1.1/cov_report.sh

.../pkg/mod/github.com/davecgh/go-spew@v1.1.1/spew/bypass.go

.../mod/github.com/davecgh/go-spew@v1.1.1/spew/bypasssafe.go

.../pkg/mod/github.com/davecgh/go-spew@v1.1.1/spew/common.go

...mod/github.com/davecgh/go-spew@v1.1.1/spew/common_test.go

.../pkg/mod/github.com/davecgh/go-spew@v1.1.1/spew/config.go

.../go/pkg/mod/github.com/davecgh/go-spew@v1.1.1/spew/doc.go

...go/pkg/mod/github.com/davecgh/go-spew@v1.1.1/spew/dump.go

...g/mod/github.com/davecgh/go-spew@v1.1.1/spew/dump_test.go

...od/github.com/davecgh/go-spew@v1.1.1/spew/dumpcgo_test.go

.../github.com/davecgh/go-spew@v1.1.1/spew/dumpnocgo_test.go

...od/github.com/davecgh/go-spew@v1.1.1/spew/example_test.go

.../pkg/mod/github.com/davecgh/go-spew@v1.1.1/spew/format.go