Revert "python-packages: SQLAlchemy: build"

This reverts commit 6e8d1f84f2.

pysqlite is not available for Python 3. Adding it to buildInputs
makes all packages dependent upon sqlalchemy equally unavailable
for no good reason.

pkgs/top-level/python-packages.nix

@@ -11909,7 +11909,7 @@ let
       md5 = "470ca4da4a0081efc830f0d90dd91682";
     };
 
-    buildInputs = with self; [ nose mock pysqlite ];
+    buildInputs = with self; [ nose mock ];
 
     propagatedBuildInputs = with self; [ modules.sqlite3 ];