redhat: rpm spec: added protobuf-c to deps & fix bogus changelog date

redhat: rpm spec: added protobuf-c to deps & fix bogus changelog date

Fixes for:
```
checking for protoc-c... no
configure: error: in `/builddir/build/BUILD/frr-frr-9.1':
configure: error: protobuf requested but protoc-c not found.  Install protobuf-c.
```

And rpmlint warnings:
```
warning: line 208: It's not recommended to have unversioned Obsoletes: Obsoletes:          gated mrt zebra frr-sysvinit
warning: bogus date in %changelog: Thu Oct 09 2023 Donatas Abraitis <donatas@opensourcerouting.org> - 9.1
    line 208: It's not recommended to have unversioned Obsoletes: Obsoletes:          gated mrt zebra frr-sysvinit
    bogus date in %changelog: Thu Oct 09 2023 Donatas Abraitis <donatas@opensourcerouting.org> - 9.1
```

Signed-off-by: Konstantin Shalygin <k0ste@k0ste.ru>