chore(ci): fix missing targets when using `go vet`

[kachick]

Currently go vet does not check many files, for example cmd/*.go

> go version
go version go1.22.2 linux/amd64

> go vet -json
# github.com/google/yamlfmt
{}
# github.com/google/yamlfmt_test
# [github.com/google/yamlfmt_test]
{}

> go vet -json ./...
# github.com/google/yamlfmt/internal/collections
{}
# github.com/google/yamlfmt/internal/assert
{}
# github.com/google/yamlfmt/internal/multilinediff
{}
# github.com/google/yamlfmt/internal/logger
{}
# github.com/google/yamlfmt/internal/collections_test
# [github.com/google/yamlfmt/internal/collections_test]
{}
# github.com/google/yamlfmt/internal/tempfile
{}
# github.com/google/yamlfmt/internal/assert_test
# [github.com/google/yamlfmt/internal/assert_test]
{}
# github.com/google/yamlfmt
{}
# github.com/google/yamlfmt/internal/hotfix
{}
# github.com/google/yamlfmt/engine
{}
# github.com/google/yamlfmt_test
# [github.com/google/yamlfmt_test]
{}
# github.com/google/yamlfmt/formatters/basic/anchors
{}
# github.com/google/yamlfmt/formatters/basic/anchors_test
# [github.com/google/yamlfmt/formatters/basic/anchors_test]
{}
# github.com/google/yamlfmt/command
{}
# github.com/google/yamlfmt/formatters/basic
{}
# github.com/google/yamlfmt/formatters/basic_test
# [github.com/google/yamlfmt/formatters/basic_test]
{}
# github.com/google/yamlfmt/cmd/yamlfmt
# [github.com/google/yamlfmt/cmd/yamlfmt]
{}

[kachick]

Thank you for merging!