Fix for Ruby 3.0

also enhance .gitignore file.

.gitignore

@@ -1,2 +1,2 @@
 /rack-*.gem
-/rack-2.2.3-tests.tar.gz
+/rack-*-tests.tar.gz

rubygem-rack.spec

@@ -20,6 +20,7 @@ BuildRequires: rubygem(concurrent-ruby)
 BuildRequires: memcached
 BuildRequires: rubygem(memcache-client)
 BuildRequires: rubygem(minitest)
+BuildRequires: rubygem(webrick)
 BuildArch: noarch
 
 %global __brp_mangle_shebangs_exclude_from ^%{gem_instdir}/test/cgi/test.ru$
@@ -56,7 +57,6 @@ mkdir -p %{buildroot}%{gem_dir}
 cp -a .%{gem_dir}/* \
         %{buildroot}%{gem_dir}/
 
-
 mkdir -p %{buildroot}%{_bindir}
 cp -a .%{_bindir}/* \
         %{buildroot}%{_bindir}/