[FIX] allow ``/oauth/userinfo`` GET request with json content-type

This is required by some services (like ``outline``)

galicea_openid_connect/controllers/main.py

@@ -410,3 +410,30 @@ class Main(http.Controller):
             response=None,
             status=302,
         )
+
+
+from odoo.http import Root, HttpRequest
+
+
+def patch_get_request(f):
+    """Allow ``/oauth/userinfo`` GET request to be accepted for outline
+
+    Outline (and probably other services) can implement OIDC by adding a
+    ``content-type`` set to "application/json". This makes odoo 14 use 
+    JsonRequest object that will refuse the request.
+   
+    This is monkey-patching, and is not meant to be a final solution, but
+    only a temporary one.
+
+    """
+
+    def patched(self, httprequest):
+        if httprequest.path == "/oauth/userinfo" and \
+           httprequest.method == "GET":
+            return HttpRequest(httprequest)
+        return f(self, httprequest)
+
+    return patched
+
+
+Root.get_request = patch_get_request(Root.get_request)