v1.4.3 (#153)

* fix(callFirestore): fix issue writing doc with `null` values - closes #150)
* chore(tests): add test to confirm null values are correctly written - #150
* build(deps): bump elliptic from 6.4.1 to 6.5.3 in /examples/basic (#152)
* build(deps): bump elliptic in /examples/react-redux-firebase (#151)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>