bumping edx-sga to v0.6.2

use PyPI version of edx-sga and move to base.txt

requirements/edx/base.txt

@@ -205,3 +205,6 @@ py2neo==3.1.2
 
 # for calculating coverage
 -r coverage.txt
+
+# Third Party XBlocks
+edx-sga==0.6.2

requirements/edx/github.txt

@@ -94,6 +94,5 @@ git+https://github.com/edx/edx-proctoring.git@0.18.0#egg=edx-proctoring==0.18.0
 git+https://github.com/edx/edx-celeryutils.git@v0.1.0#egg=edx-celeryutils==0.1.0
 
 # Third Party XBlocks
--e git+https://github.com/mitodl/edx-sga@172a90fd2738f8142c10478356b2d9ed3e55334a#egg=edx-sga
 git+https://github.com/open-craft/xblock-poll@v1.2.5#egg=xblock-poll==1.2.5
 git+https://github.com/edx-solutions/xblock-drag-and-drop-v2@v2.0.15#egg=xblock-drag-and-drop-v2==2.0.15