Use python 3.9 to build dependencies

requirements/production.txt

@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile with python 3.7
+# This file is autogenerated by pip-compile with python 3.9
 # To update, run:
 #
 #    pip-compile --output-file=requirements/production.txt requirements/production.in
@@ -64,8 +64,6 @@ gunicorn==20.1.0
     # via -r requirements/production.in
 idna==3.3
     # via requests
-importlib-metadata==4.11.4
-    # via kombu
 inflection==0.5.1
     # via drf-yasg
 itypes==1.2.0
@@ -124,10 +122,6 @@ soupsieve==2.3.2.post1
     # via beautifulsoup4
 sqlparse==0.4.2
     # via django
-typing-extensions==4.2.0
-    # via
-    #   asgiref
-    #   importlib-metadata
 uritemplate==4.1.1
     # via
     #   coreapi
@@ -144,8 +138,6 @@ wcwidth==0.2.5
     # via ftfy
 webencodings==0.5.1
     # via bleach
-zipp==3.8.0
-    # via importlib-metadata
 
 # The following packages are considered to be unsafe in a requirements file:
 # setuptools