fix linter issues (#57)

* fix linter issues

* use go 1.21.*

.github/workflows/gochecks.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Setup Go environment
         uses: actions/setup-go@v5
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           check-latest: true
       - name: Run golangci-lint
         uses: golangci/golangci-lint-action@v4

http_logging_test.go

@@ -6,7 +6,7 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"crypto/x509/pkix"
-	"fmt"
+	"errors"
 	"log"
 	"net/http"
 	"net/url"
@@ -64,7 +64,7 @@ func (n *NullHTTPWriter) Write(b []byte) (int, error) {
 		panic("some fake http write panic")
 	}
 	if n.doErr {
-		return 0, fmt.Errorf("some fake http write error")
+		return 0, errors.New("some fake http write error")
 	}
 	return len(b), nil
 }

logger_test.go

@@ -620,7 +620,7 @@ func TestLoggerFatalCliMode(t *testing.T) {
 func TestLoggerFatalExitOverride(t *testing.T) {
 	SetDefaultsForClientTools()
 	exitCalled := false
-	Config.FatalExit = func(code int) {
+	Config.FatalExit = func(_ int) {
 		exitCalled = true
 	}
 	Fatalf("testing log.Fatalf exit case")
@@ -769,7 +769,7 @@ func TestSerializationOfError(t *testing.T) {
 	if kvStr != expected {
 		t.Errorf("unexpected:\n%s\nvs:\n%s\n", kvStr, expected)
 	}
-	err = fmt.Errorf("test error")
+	err = errors.New("test error")
 	Errf("Error on purpose: %v", err)
 	S(Error, "Error on purpose", Any("err", err))
 	kv = Any("err", err)