Upadate embedded Git binary and create new release

According to security advisory "Multiple Products Security Advisory - Git Buffer Overflow - CVE-2022-41903, CVE-2022-23521" Sourcetree should be updated to version 3.4.12 after release or switch to an external updated git version as mitigation. 

https://confluence.atlassian.com/security/multiple-products-security-advisory-git-buffer-overflow-cve-2022-41903-cve-2022-23521-1189805967.html