fix: pinned requirements versions (fixes #168)

requirements.txt

@@ -1,13 +1,15 @@
-Crypto
+crypto==1.4.1
-requests
+requests==2.21.0
-pyyaml
+PyYAML==3.13
-scapy
+scapy==2.4.3
-gym
+gym==0.14.0
-stable-baselines
+stable-baselines==2.7.0
-tensorflow
+tensorflow==1.13.1
-tweepy
+tensorflow-estimator==1.14.0
-file_read_backwards
+tweepy==3.6.0
-numpy
+file-read-backwards==2.0.0
-inky
+numpy==1.17.2
-smbus
+inky==0.0.5
-pillow
+smbus2==0.3.0
+Pillow==5.4.1
+spidev==3.4