Make libressl-devel dependency explicit - the final binary is linked
against it; libgit2 isn't being used for the final binary because
libgit2-sys now requires libgit2>=1.1.0, but we leave it in for when
it's updated and starship gets rebuilt.
libgit2-devel is also required on host now - it isn't picked up either.
Building the vendored libgit2 requires zlib-devel, which libgit2-devel
depends on, so the dependency is fullfilled indirectly. When the
libgit2 package is updated, the build should pick it up.
Closes: #28310 [via git-merge-pr]
b63e44af0d