core: upgrade Go requirement to 1.26.0 (#8466)

* core: upgrade Go requirement to 1.26.0

As golang 1.27 has been released, this PR
- Bump Go version requirement to 1.26.0
- Update Go build version to 1.27.0

This is also for solving the issue encountered in 8092 of k8s update

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Bump golang ci

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Fix

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Fix

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Fix

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Migrate faillint to forbidigo, as failint has not bee updated for more than a year

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

---------

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

plugin/pkg/proxy/doq_test.go

@@ -176,12 +176,12 @@ func makeDoQTestTLSConfigs(t *testing.T) (*tls.Config, *tls.Config) {
 	}
 	roots.AddCert(parsed)
 	return &tls.Config{
-			Certificates: []tls.Certificate{cert},
-			NextProtos:   []string{doqALPN},
-		}, &tls.Config{
-			RootCAs:    roots,
-			ServerName: "doq.test",
-		}
+		Certificates: []tls.Certificate{cert},
+		NextProtos:   []string{doqALPN},
+	}, &tls.Config{
+		RootCAs:    roots,
+		ServerName: "doq.test",
+	}
 }
 
 func writeDoQTestResponse(stream *quic.Stream, response *dns.Msg) error {
@@ -291,8 +291,7 @@ func TestProxyDoQVerifiesServerName(t *testing.T) {
 	if err == nil {
 		t.Fatal("Connect() succeeded with the wrong TLS server name")
 	}
-	var hostnameError x509.HostnameError
-	if !errors.As(err, &hostnameError) {
+	if _, ok := errors.AsType[x509.HostnameError](err); !ok {
 		t.Fatalf("Connect() error = %T %v, want x509.HostnameError", err, err)
 	}
 }