setup: remove dependency on pyserial 2.7

We should remove the dependency on pysieral 2.7 as python 2.7 is
being deprecated.

BUG=b:159192174
TEST=Bluetooth related tests passed.

Change-Id: I76daabb36b3e5a2a07a8a91c4bc6d0cd8cd50e51
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/chameleon/+/2846139
Reviewed-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Reviewed-by: Michael Sun <michaelfsun@google.com>
Commit-Queue: Michael Sun <michaelfsun@google.com>
Tested-by: Michael Sun <michaelfsun@google.com>
diff --git a/setup.py b/setup.py
index 1c91021..72c3ddf 100644
--- a/setup.py
+++ b/setup.py
@@ -20,9 +20,7 @@
     license='Chromium',
     description='Server to communicate and control Chameleon board.',
     long_description='Server to communicate and control Chameleon board.',
-    # Uses pyserial version 2.7. The newer 3.x version is not compatible
-    # with chameleond/utils/serial_utils.py
-    install_requires=['pyserial==2.7', 'schedule', 'future'],
+    install_requires=['schedule', 'future'],
     scripts=['utils/lock_u_boot_console', 'utils/run_chameleond',
              'utils/run_displayd', 'utils/run_stream_server',
              'chameleond/utils/server_time', 'utils/run_scheduler',