fix(dashboard): set headers for JWKS requests

plugins/dashboard_auth/self_hosted/__init__.py

@@ -601,6 +601,10 @@ class SelfHostedOIDCProvider(DashboardAuthProvider):
                 disco["jwks_uri"],
                 cache_keys=True,
                 lifespan=_JWKS_CACHE_SECONDS,
+                headers={
+                    "Accept": "application/json",
+                    "User-Agent": "HermesAgent/1.0",
+                },
             )
         return self._jwks_client