update python dependancies

requirements.txt

@@ -1,11 +1,11 @@
 envbash==1.2.0
+# The following packages should ideally be installed through apt
+# For the moment, I am pinning their versions here to the ones available in debian bullseye
 ephem==3.7.7.1
-idna==2.8
+idna==2.10
 jsonschema==3.2.0
 matplotlib==3.3.4
-numpy==1.18.1
-Pillow==7.1.2
-pylab==0.0.1
-pyyaml==5.4.1
+numpy==1.19.5
+Pillow==8.1.2
+pyyaml==5.3.1
 requests==2.25.1
-urllib3==1.26.3