pip 20.3 use new dependency resolver that breaks current config

Disables the new resolver (https://pip.pypa.io/en/stable/user_guide/#deprecation-timeline). We should fix the dependency tree at some point - this will be removed in pip@21.0

debian-template/postinst

@@ -26,8 +26,8 @@ fi
 
 echo "Installing python dependencies"
 {
-  source /usr/lib/smasch/env/bin/activate && pip install -r /usr/lib/smasch/requirements.txt --log $LOG_FILE
-  source /usr/lib/smasch/env/bin/activate && pip install -r /usr/lib/smasch/requirements-dev.txt  --log $LOG_FILE
+  source /usr/lib/smasch/env/bin/activate && pip install -r --use-deprecated=legacy-resolver /usr/lib/smasch/requirements.txt --log $LOG_FILE
+  source /usr/lib/smasch/env/bin/activate && pip install -r --use-deprecated=legacy-resolver /usr/lib/smasch/requirements-dev.txt  --log $LOG_FILE
 } || {
   echo "There was an issue when installing python dependencies." >> $LOG_FILE
   echo "There was an issue when installing python dependencies. Reinstall of smasch could help (in case you are upgrading smasch the data should not be lost in the process): "