rpm: Add pytest as dependency

I thought this would be added automatically, based on [1]. Apparently
not.

[1] https://docs.fedoraproject.org/en-US/packaging-guidelines/Python/#_test_dependencies_2

Signed-off-by: Stephen Finucane <stephen@that.guru>

Author: stephenfin

rpm/git-pw.spec

@@ -12,6 +12,7 @@ BuildArch:      noarch
 BuildRequires:  python3-devel
 BuildRequires:  python3-pbr
 BuildRequires:  python3-setuptools
+BuildRequires:  python3-pytest
 
 Requires:       git