[v15.0/forgejo]: chore: add modernizer linter (#11949)

**Backport: !11936**

- Go has a suite of small linters that helps with modernizing Go code by using newer functions and catching small mistakes, https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize.
- Enable this linter in golangci-lint.
- There's also [`go fix`](https://go.dev/blog/gofix), which is not yet released as a linter in golangci-lint: https://github.com/golangci/golangci-lint/pull/6385

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/11949
Reviewed-by: Mathieu Fenniak <mfenniak@noreply.codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>

modules/packages/npm/creator.go

@@ -58,7 +58,7 @@ type PackageMetadata struct {
 	Time           map[string]time.Time               `json:"time,omitempty"`
 	Homepage       string                             `json:"homepage,omitempty"`
 	Keywords       []string                           `json:"keywords,omitempty"`
-	Repository     Repository                         `json:"repository,omitempty"`
+	Repository     Repository                         `json:"repository"`
 	Author         User                               `json:"author"`
 	ReadmeFilename string                             `json:"readmeFilename,omitempty"`
 	Users          map[string]bool                    `json:"users,omitempty"`
@@ -75,7 +75,7 @@ type PackageMetadataVersion struct {
 	Author               User                `json:"author"`
 	Homepage             string              `json:"homepage,omitempty"`
 	License              string              `json:"license,omitempty"`
-	Repository           Repository          `json:"repository,omitempty"`
+	Repository           Repository          `json:"repository"`
 	Keywords             []string            `json:"keywords,omitempty"`
 	Dependencies         map[string]string   `json:"dependencies,omitempty"`
 	BundleDependencies   []string            `json:"bundleDependencies,omitempty"`

modules/packages/npm/metadata.go

@@ -22,5 +22,5 @@ type Metadata struct {
 	OptionalDependencies    map[string]string `json:"optional_dependencies,omitempty"`
 	Bin                     map[string]string `json:"bin,omitempty"`
 	Readme                  string            `json:"readme,omitempty"`
-	Repository              Repository        `json:"repository,omitempty"`
+	Repository              Repository        `json:"repository"`
 }

modules/packages/nuget/symbol_extractor.go

@@ -142,8 +142,8 @@ func ParseDebugHeaderID(r io.ReadSeeker) (string, error) {
 			if _, err := r.Read(b); err != nil {
 				return "", err
 			}
-			if i := bytes.IndexByte(b, 0); i != -1 {
-				buf.Write(b[:i])
+			if before, _, ok := bytes.Cut(b, []byte{0}); ok {
+				buf.Write(before)
 				return buf.String(), nil
 			}
 			buf.Write(b)

modules/packages/rubygems/marshal.go

@@ -91,7 +91,7 @@ func (e *MarshalEncoder) marshal(v any) error {
 	val := reflect.ValueOf(v)
 	typ := reflect.TypeOf(v)
 
-	if typ.Kind() == reflect.Ptr {
+	if typ.Kind() == reflect.Pointer {
 		val = val.Elem()
 		typ = typ.Elem()
 	}
@@ -250,7 +250,7 @@ func (e *MarshalEncoder) marshalArray(arr reflect.Value) error {
 		return err
 	}
 
-	for i := 0; i < length; i++ {
+	for i := range length {
 		if err := e.marshal(arr.Index(i).Interface()); err != nil {
 			return err
 		}

modules/packages/swift/metadata.go

@@ -47,7 +47,7 @@ type Metadata struct {
 	Keywords      []string             `json:"keywords,omitempty"`
 	RepositoryURL string               `json:"repository_url,omitempty"`
 	License       string               `json:"license,omitempty"`
-	Author        Person               `json:"author,omitempty"`
+	Author        Person               `json:"author"`
 	Manifests     map[string]*Manifest `json:"manifests,omitempty"`
 }