update requirements

requirements/dev.txt

@@ -78,6 +78,8 @@ flask-admin==1.5.7
     # via -r requirements/dev.in
 flask-bs4==4.5.3.0
     # via -r requirements/dev.in
+flask-caching==1.10.1
+    # via -r requirements/dev.in
 flask-cors==3.0.10
     # via -r requirements/dev.in
 flask-db==0.3.1
@@ -101,6 +103,7 @@ flask==1.1.2
     #   -r requirements/build.in
     #   flask-admin
     #   flask-bs4
+    #   flask-caching
     #   flask-cors
     #   flask-db
     #   flask-fixtures