Fix yast2 extension registration error dialog (#361)

Correctly check for the new connection.ApiError

When checking to see if an APIError has occurred we need to check for an
error being an instance of the new version of the error object, as found
in the pkg/connection package, rather than the old version defined in
internal/connect.
    
This ensures that when this type of error occurs then it is correctly
detected as an APIError and reported as such to the Ruby bindinsg that
call libsuseconnect.

Update package .changes file.

Co-Authored-By: esampson@suse.com

Author: rtamalin

build/packaging/suseconnect-ng.changes

@@ -11,6 +11,7 @@ Thu Mar 12 18:53:13 UTC 2026 - Felix Schnizlein <fschnizlein@suse.com>
     (jsc#TEL-260).
   - Removed backport patch: fix-libsuseconnect-and-pci.patch
   - Add missing product id to allow yast2-registration to not break (bsc#1257825)
+  - Fix libsuseconnect APIError detection logic (bsc#1257825)
 
 -------------------------------------------------------------------
 Wed Mar  4 16:48:14 UTC 2026 - Felix Schnizlein <fschnizlein@suse.com>

third_party/libsuseconnect/libsuseconnect.go

@@ -21,6 +21,7 @@ import (
 	"github.com/SUSE/connect-ng/internal/connect"
 	cred "github.com/SUSE/connect-ng/internal/credentials"
 	"github.com/SUSE/connect-ng/internal/util"
+	"github.com/SUSE/connect-ng/pkg/connection"
 	"github.com/SUSE/connect-ng/pkg/registration"
 	"github.com/SUSE/connect-ng/pkg/search"
 )
@@ -303,7 +304,7 @@ func errorToJSON(err error) string {
 		// TODO: add other values as needed
 	}
 
-	if ae, ok := err.(connect.APIError); ok {
+	if ae, ok := err.(*connection.ApiError); ok {
 		s.ErrType = "APIError"
 		s.Code = ae.Code
 		s.Message = ae.Message