[build]: add fastentrypoints which is used for sonic-utilities build (#2479)

sonic-net/sonic-utilities#438

Signed-off-by: Wataru Ishida <[email protected]>

Author: ishidawataru

sonic-slave/Dockerfile

@@ -265,7 +265,7 @@ RUN pip install --force-reinstall --upgrade jinja2>=2.10
 RUN pip install j2cli
 
 # For sonic utilities testing
-RUN pip install click-default-group click natsort tabulate netifaces==0.10.7
+RUN pip install click-default-group click natsort tabulate netifaces==0.10.7 fastentrypoints
 
 # For supervisor build
 RUN pip install meld3 mock