chore(deps): bump chroma to v2 #735

Bump `alecthomas/chroma` to `v2`:
https://github.com/cheat/cheat/issues/735

vendor/github.com/alecthomas/chroma/v2/lexers/dns.go

@@ -0,0 +1,17 @@
+package lexers
+
+import (
+	"regexp"
+)
+
+// TODO(moorereason): can this be factored away?
+var zoneAnalyserRe = regexp.MustCompile(`(?m)^@\s+IN\s+SOA\s+`)
+
+func init() { // nolint: gochecknoinits
+	Get("dns").SetAnalyser(func(text string) float32 {
+		if zoneAnalyserRe.FindString(text) != "" {
+			return 1.0
+		}
+		return 0.0
+	})
+}