update satpy hash to post-https://github.com/pytroll/satpy/pull/1548, with...

update satpy hash to post-https://github.com/pytroll/satpy/pull/1548, with support for modifying the environment prefix

buildbucket/buildbucket_environment.yaml

@@ -27,4 +27,4 @@ dependencies:
     - git+https://github.com/deeplycloudy/lmatools.git@minvaluegrids
     - git+https://github.com/deeplycloudy/stormdrain.git
     - git+https://github.com/deeplycloudy/glmtools.git@master
-    - git+https://github.com/pytroll/satpy.git@7ae7b274a01e5e170bd2cf0f18ccf53b0bd33ada
\ No newline at end of file
+    - git+https://github.com/pytroll/satpy.git@3544d60940dba9129499ac3ee303c0705a9ddf7b
\ No newline at end of file