Version number bumped to 0.19.11

Summary: Title

Test Plan:

make check
./bitcoind --version
./bitcoin-cli --version
./bitcoin-qt --version

All should output 0.19.11

Reviewers: deadalnix, Fabien, jasonbcox, O1 Bitcoin ABC, #bitcoin_abc, Mengerian

Reviewed By: jasonbcox, O1 Bitcoin ABC, #bitcoin_abc, Mengerian

Subscribers: Mengerian

Differential Revision: https://reviews.bitcoinabc.org/D3667