providers/oauth2: use simpler charset for refresh tokens (#5502)

various implementations might have issues with the special chars

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

authentik/providers/oauth2/migrations/0016_alter_refreshtoken_token.py

@@ -0,0 +1,24 @@
+# Generated by Django 4.1.7 on 2023-05-06 16:18
+
+from django.db import migrations, models
+
+import authentik.providers.oauth2.models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        (
+            "authentik_providers_oauth2",
+            "0015_accesstoken_auth_time_authorizationcode_auth_time_and_more",
+        ),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="refreshtoken",
+            name="token",
+            field=models.TextField(
+                default=authentik.providers.oauth2.models.generate_client_secret
+            ),
+        ),
+    ]

authentik/providers/oauth2/models.py

@@ -382,7 +382,7 @@ class AccessToken(SerializerModel, ExpiringModel, BaseGrantModel):
 class RefreshToken(SerializerModel, ExpiringModel, BaseGrantModel):
     """OAuth2 Refresh Token, opaque"""
 
-    token = models.TextField(default=generate_key)
+    token = models.TextField(default=generate_client_secret)
     _id_token = models.TextField(verbose_name=_("ID Token"))
 
     @property