fsmonitor: migrate Python ABCs from collections to collections.abc
The Collections Abstract Base Classes in the collections module are
deprecated since Python 3.3 in favor of collections.abc, and removed
in Python 3.10.
Same with share-safe
$ echo "[format]" >> $HGRCPATH
$ echo "use-share-safe = True" >> $HGRCPATH
$ cd $TESTTMP
$ hg init myrepo
$ cd myrepo
$ cat > .hg/hgrc <<EOF
> [extensions]
> sparse=
> EOF
$ echo a > show
$ echo x > hide
$ hg ci -Aqm 'initial'
Regression test: checks that this command correctly locks the store
before updating the store [requirements] config.
$ hg up -q 0
$ hg debugsparse --include 'hide'