modernize pylint

Turns out that the pylint setup was failing silently for a long time now. Due to other bugs in pylint, full errors needed to be ignored. But a failing import also was a full error, so pylint was never running. This fixes that, and the open issues. This is a conservative pylint config. For anyone to wants to enable more checks, they should open a merge request that enables those checks and then includes all the required fixes.

tests/complete-ci-tests

@@ -90,9 +90,12 @@ sh hooks/pre-commit
 pylint=/usr/bin/pylint3
 if [ -e $pylint ]; then
     cd $WORKSPACE
-    # call with 'python3' to use the pyvenv so pylint checks against its installed libs
-    python3 $pylint \
-            --rcfile=.pylint-rcfile \
-            --output-format=parseable --reports=n \
-            fdroidserver/*.py fdroid makebuildserver setup.py > $WORKSPACE/pylint.parseable
+    # call with 'python3' to force pylint to use the pyvenv and its libs
+    python3 $pylint --rcfile=.pylint-rcfile --output-format=colorized --reports=n \
+            fdroid \
+            makebuildserver \
+            setup.py \
+            fdroidserver/*.py \
+            tests/*.py \
+            tests/*.TestCase
 fi