docs: add Leisterbecker as a contributor for code (#1935)

* docs: update README.md [skip ci]

* docs: update .all-contributorsrc [skip ci]

Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>

allcontributors[bot] committed 4y ago

f670ae547b9bd03bcd06751caea3779d90d228b8

Parent: df73d80

Committed by GitHub <noreply@github.com> on 12/23/2021, 6:45:14 PM