Add dependency on ca-certificates to fix build on OBS

Commit 8c611a0f "Fix TLS connections by explicitly setting CERT_LOCATION" tried to unbreak HTTPS connections by forcing the location of /etc/ssl/certs/ca-certificates.crt, but it made build fail on OBS because the buildsystem actually tries to check the existence of the file at build time. Unlike on the Debian buildds, such file is not available by default in the build chroots created by OBS since ca-certificates is not in the pre-installed set.

Add the build-dependency on ca-certificates to ensure it is available during the build on OBS.

The Debian upstream packaging also added the build-dep with the commit from Sudip Mukherjee sudipm.mukherjee@gmail.com:

Add dependency on ca-certificates and libpcre3-dev

https://salsa.debian.org/debian/libgit2/-/commit/86ca7244128f1df7d1b24