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/internal/tz.go

@@ -0,0 +1,36 @@
+package internal
+
+import "time"
+
+// Timezones used for local datetime, date, and time TOML types.
+//
+// The exact way times and dates without a timezone should be interpreted is not
+// well-defined in the TOML specification and left to the implementation. These
+// defaults to current local timezone offset of the computer, but this can be
+// changed by changing these variables before decoding.
+//
+// TODO:
+// Ideally we'd like to offer people the ability to configure the used timezone
+// by setting Decoder.Timezone and Encoder.Timezone; however, this is a bit
+// tricky: the reason we use three different variables for this is to support
+// round-tripping – without these specific TZ names we wouldn't know which
+// format to use.
+//
+// There isn't a good way to encode this right now though, and passing this sort
+// of information also ties in to various related issues such as string format
+// encoding, encoding of comments, etc.
+//
+// So, for the time being, just put this in internal until we can write a good
+// comprehensive API for doing all of this.
+//
+// The reason they're exported is because they're referred from in e.g.
+// internal/tag.
+//
+// Note that this behaviour is valid according to the TOML spec as the exact
+// behaviour is left up to implementations.
+var (
+	localOffset   = func() int { _, o := time.Now().Zone(); return o }()
+	LocalDatetime = time.FixedZone("datetime-local", localOffset)
+	LocalDate     = time.FixedZone("date-local", localOffset)
+	LocalTime     = time.FixedZone("time-local", localOffset)
+)