ci: bump to go 1.23 (#453)

Upgrade to Go 1.23.

Upgrade also requires bumping `golangci-lint` to v1.62.2, and upgrading
third-party test versions for some failing cases.

tests/thirdparty/config_test.go

@@ -94,7 +94,6 @@ func TestValidateErrors(t *testing.T) {
 		},
 	}
 	for _, c := range cases {
-		c := c // scopelint
 		t.Run(c.Name, func(t *testing.T) {
 			err := c.Item.Validate()
 			if err == nil {