Revert "Add asynchronous downloading to speed up signed URL downloadi… (

#4302)

…ng. (#4266)"

This reverts commit 2ca47ed.

We should test this first.

src/Pipfile

@@ -40,10 +40,9 @@ redis = "==3.3.11"
 requests = "==2.21.0"
 sendgrid = "==6.0.4"
 wrapt = "==1.16.0"
+
 # Hack: We are using this to specify App Engine packages,
 # since there is no support for custom package sets.
-aiohttp = "==3.10.5"
-
 [dev-packages]
 charset-normalizer = "==3.3.2"
 firebase-admin = "==6.2.0"
@@ -52,4 +51,4 @@ itsdangerous = "==2.0.1"
 Jinja2 = "==3.1.4"
 PyJWT = "==2.7.0"
 requests-toolbelt = "==0.9.1"
-werkzeug = "==2.2.2"
+werkzeug = "==2.2.2"