[toolsutils] Small fixes to fill_templated_file() * Use context managers to close _both_ files * Use io.open to enforce text mode on both python 2 and 3

[skeleton] Fix broken spec file template Broken in commit 73c1c9cf6bda.

[devtools] Fix fd leak in tests

[devtools] stop using datetime.now() in cwctl newcube and i18ncube

[hooks] fix timestamp confusion in DataImportsCleanupStartupHook CWDataImport.start_timestamp is inserted as datetime.utcnow(), in server/sources/datafeed.py:DataFeedSourceinit_import_log. Don't compare it to datetime.now().

[hooks] fix timestamp confusion in TransactionsCleanupStartupHook transactions.tx_time is inserted as datetime.utcnow(), in server/sources/native.py:NativeSQLSource.start_undoable_transaction. Don't compare it to datetime.now().

merge with 3.21.3 The change in unittest_serverctl.py is needed because of daef7ce08fea (from 3.20.11) and 3914388b2d0f (from the 3.22 branch). Due to both changes, CubicWebTC.config.repository no longer creates a new repository (and thus, a new connection). Since both DBDumpCommand and CubicWebTC.tearDown try to shutdown the repo, tearDown breaks apart. The solution is to temporarily disable ServerConfiguration's config cache. By forcing DBDumpCommand to get a new configuration object, it then gets its own Repo object, allowing tearDown and DBDumpCommand to work independently.

Added tag 3.21.3, debian/3.21.3-1, centos/3.21.3-1 for changeset 9edfe9429209