rpm: add missing rpm spec file template ; fixes 309ce6c5

src/main/rpm/dcache-cta.spec

+Summary: dCache nearline storage provider for CTA
+Vendor: dCache.org
+Name: dcache-cta
+URL: https://dcache.org
+Packager: dCache.org <support@dcache.org>
+License: Distributable
+Group: Applications/System
+
+Version: @dist.version@
+Release: 1
+BuildArch: noarch
+Prefix: /
+
+AutoReqProv: no
+Requires: dcache >= 7.2.2
+
+Source0: %{name}-%{version}.tar.gz
+
+%description
+dCache Nearline storage provider for integration with CERN Tape Archive (CTA)
+
+%prep
+%setup -q -a 0 -n %{name}-%{version}
+
+%install
+mkdir -p %{buildroot}%{_datadir}/dcache/plugins
+cp -a %{name}-%{version} %{buildroot}%{_datadir}/dcache/plugins
+
+%files
+%defattr(-,root,root,-)
+%{_datadir}
+
+%changelog
+* Wed Dec 22 2021 Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
+- Initialize package creation
\ No newline at end of file