Add platform conditional for uvloop in requirements.txt

src/Dockerfile

@@ -5,7 +5,6 @@ RUN apk --no-cache add build-base
 WORKDIR /app
 ADD requirements.txt /app
 RUN pip install --trusted-host pypi.python.org -r requirements.txt
-RUN pip install --trusted-host pypi.python.org uvloop
 
 ADD . /app
 

src/requirements.txt

@@ -4,4 +4,5 @@ asyncpg
 dateparser
 https://github.com/Rapptz/discord.py/archive/860d6a9ace8248dfeec18b8b159e7b757d9f56bb.zip#egg=discord.py
 humanize
+uvloop; sys.platform != 'win32' and sys.platform != 'cygwin' and sys.platform != 'cli'
 ciso8601