feat: update to go modules

vendor/github.com/alecthomas/chroma/lexers/b/bnf.go

@@ -1,24 +0,0 @@
-package b
-
-import (
-	. "github.com/alecthomas/chroma" // nolint
-	"github.com/alecthomas/chroma/lexers/internal"
-)
-
-// Bnf lexer.
-var Bnf = internal.Register(MustNewLexer(
-	&Config{
-		Name:      "BNF",
-		Aliases:   []string{"bnf"},
-		Filenames: []string{"*.bnf"},
-		MimeTypes: []string{"text/x-bnf"},
-	},
-	Rules{
-		"root": {
-			{`(<)([ -;=?-~]+)(>)`, ByGroups(Punctuation, NameClass, Punctuation), nil},
-			{`::=`, Operator, nil},
-			{`[^<>:]+`, Text, nil},
-			{`.`, Text, nil},
-		},
-	},
-))