fix(generate): format using goimports

this should make sure the imports are sorted

internal/muxt/routes.go

@@ -242,7 +242,7 @@ func TemplateRoutesFile(wd string, logger *log.Logger, config RoutesFileConfigur
 		file.Decls = append(file.Decls, executeFuncDecl(imports, config.TemplatesVariable))
 	}
 
-	return source.Format(file), nil
+	return source.FormatFile(filepath.Join(wd, DefaultOutputFileName), file)
 }
 
 func appendParseArgumentStatements(statements []ast.Stmt, t Template, imports *source.Imports, sigs map[string]*types.Signature, parsed map[string]struct{}, receiver *types.Named, call *ast.CallExpr) ([]ast.Stmt, error) {

internal/source/go.go

@@ -10,6 +10,8 @@ import (
 	"net/http"
 	"strconv"
 	"strings"
+
+	"golang.org/x/tools/imports"
 )
 
 func IterateGenDecl(files []*ast.File, tok token.Token) func(func(*ast.File, *ast.GenDecl) bool) {
@@ -40,6 +42,22 @@ func IterateValueSpecs(files []*ast.File) func(func(*ast.File, *ast.ValueSpec) b
 	}
 }
 
+func FormatFile(filePath string, node ast.Node) (string, error) {
+	var buf bytes.Buffer
+	if err := printer.Fprint(&buf, token.NewFileSet(), node); err != nil {
+		return "", fmt.Errorf("formatting error: %v", err)
+	}
+	out, err := imports.Process(filePath, buf.Bytes(), &imports.Options{
+		Fragment:  true,
+		AllErrors: true,
+		Comments:  true,
+	})
+	if err != nil {
+		return "", fmt.Errorf("formatting error: %v", err)
+	}
+	return string(bytes.ReplaceAll(out, []byte("\n}\nfunc "), []byte("\n}\n\nfunc "))), nil
+}
+
 func Format(node ast.Node) string {
 	var buf bytes.Buffer
 	if err := printer.Fprint(&buf, token.NewFileSet(), node); err != nil {