Adds srpm_build_deps to Packit config

I have no idea what I'm doing but I glanced at the docs in [this][1]
and [this][2] and feel like I'm on the right track to silencing the
warnings.

[1]: https://packit.dev/posts/copr-srpms/#deployment-phases
[2]: https://packit.dev/docs/configuration/#srpm_build_deps

.packit.yml

@@ -15,3 +15,8 @@ jobs:
   metadata:
     targets:
     - fedora-all
+
+srpm_build_deps:
+  - python3-pip
+  - python3-setuptools_scm
+