Update to wagtail-cache==2.1.0

Chagelog: https://github.com/coderedcorp/wagtail-cache/compare/v1.0.2...v2.1.0

requirements.txt

@@ -46,7 +46,7 @@ psycopg2-binary
 reportlab==3.6.3
 social_auth_app_django==5.0.0
 tomd==0.1.3
-wagtail-cache==1.0.2
+wagtail-cache==2.1.0
 wagtail-purge==0.2
 wagtail==3.0.1
 whitenoise==5.3.0