staticcheck (#313)

* CI: use staticcheck for linting

This commit switches the linter for Go code from golint to staticcheck.
Golint has been deprecated since last year and staticcheck is a
recommended replacement.

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

* revendor

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

* cmd,pkg: fix lint warnings

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

vendor/github.com/BurntSushi/toml/decode_go116.go

@@ -0,0 +1,18 @@
+// +build go1.16
+
+package toml
+
+import (
+	"io/fs"
+)
+
+// DecodeFS is just like Decode, except it will automatically read the contents
+// of the file at `path` from a fs.FS instance.
+func DecodeFS(fsys fs.FS, path string, v interface{}) (MetaData, error) {
+	fp, err := fsys.Open(path)
+	if err != nil {
+		return MetaData{}, err
+	}
+	defer fp.Close()
+	return NewDecoder(fp).Decode(v)
+}