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/styles/api.go

@@ -0,0 +1,65 @@
+package styles
+
+import (
+	"embed"
+	"io/fs"
+	"sort"
+
+	"github.com/alecthomas/chroma/v2"
+)
+
+//go:embed *.xml
+var embedded embed.FS
+
+// Registry of Styles.
+var Registry = func() map[string]*chroma.Style {
+	registry := map[string]*chroma.Style{}
+	// Register all embedded styles.
+	files, err := fs.ReadDir(embedded, ".")
+	if err != nil {
+		panic(err)
+	}
+	for _, file := range files {
+		if file.IsDir() {
+			continue
+		}
+		r, err := embedded.Open(file.Name())
+		if err != nil {
+			panic(err)
+		}
+		style, err := chroma.NewXMLStyle(r)
+		if err != nil {
+			panic(err)
+		}
+		registry[style.Name] = style
+		_ = r.Close()
+	}
+	return registry
+}()
+
+// Fallback style. Reassign to change the default fallback style.
+var Fallback = Registry["swapoff"]
+
+// Register a chroma.Style.
+func Register(style *chroma.Style) *chroma.Style {
+	Registry[style.Name] = style
+	return style
+}
+
+// Names of all available styles.
+func Names() []string {
+	out := []string{}
+	for name := range Registry {
+		out = append(out, name)
+	}
+	sort.Strings(out)
+	return out
+}
+
+// Get named style, or Fallback.
+func Get(name string) *chroma.Style {
+	if style, ok := Registry[name]; ok {
+		return style
+	}
+	return Fallback
+}