Change filter with lambda to list comprehension

It is more readable and returns a list therefore it is compatible both
with Python 2 and 3.

Signed-off-by: Łukasz Żarnowiecki <dolohow@outlook.com>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

test/OLItest/TestRunner.py

@@ -131,9 +131,7 @@ class OLITestLib():
         else:
             sections = [r for r in config.sections() \
                             if r.startswith('Repository')]
-            sections = filter(lambda s: \
-                                  config.get(s, 'Type').lower() == 'imap',
-                              sections)
+            sections = [s for s in sections if config.get(s, 'Type').lower() == 'imap']
         for sec in sections:
             # Connect to each IMAP repo and delete all folders
             # matching the folderfilter setting. We only allow basic