build: Properly pin mypy based on django-stubs compatibility.

Django stubs by default doesn't pin mypy but has an extras that does
properly pin it to versions that are compatible.  For us it doesn't make
sense to not use this extra as we will always need a version of Mypy
that works with djnago-stubs.

requirements/edx/development.in

@@ -17,7 +17,7 @@
 
 click                                   # Used for perf_tests utilities in modulestore
 django-debug-toolbar                    # A set of panels that display debug information about the current request/response
-django-stubs                            # Typing stubs for Django, so it works with mypy
+django-stubs[compatible-mypy]           # Typing stubs for Django, so it works with mypy
 djangorestframework-stubs               # Typing stubs for DRF
 mypy                                    # static type checking
 pywatchman                              # More efficient checking for runserver reload trigger events

requirements/edx/development.txt

@@ -571,7 +571,7 @@ django-storages==1.14.6
     #   -r requirements/edx/doc.txt
     #   -r requirements/edx/testing.txt
     #   edxval
-django-stubs==5.2.0
+django-stubs[compatible-mypy]==5.2.0
     # via
     #   -c requirements/edx/../constraints.txt
     #   -r requirements/edx/development.in
@@ -1278,8 +1278,10 @@ multidict==6.4.4
     #   -r requirements/edx/testing.txt
     #   aiohttp
     #   yarl
-mypy==1.16.0
-    # via -r requirements/edx/development.in
+mypy==1.15.0
+    # via
+    #   -r requirements/edx/development.in
+    #   django-stubs
 mypy-extensions==1.1.0
     # via mypy
 mysqlclient==2.2.7
@@ -1427,8 +1429,6 @@ path-py==12.5.0
     #   edx-enterprise
     #   ora2
     #   staff-graded-xblock
-pathspec==0.12.1
-    # via mypy
 pbr==6.1.1
     # via
     #   -r requirements/edx/doc.txt