CTA now depends on protobuf3

cta.spec.in

@@ -42,7 +42,7 @@ BuildRequires: xrootd-devel         = 1:4.4.1
 BuildRequires: xrootd-server-devel  = 1:4.4.1
 BuildRequires: xrootd-private-devel = 1:4.4.1
 BuildRequires: librados-devel >= 11.0, libradosstriper-devel >= 11.0, 
-BuildRequires: protobuf-compiler >= 2.3.0 protobuf-devel >= 2.3.0
+BuildRequires: protobuf3-compiler >= 3.2.0 protobuf3-devel >= 3.2.0
 BuildRequires: gmock-devel >= 1.5.0 gtest-devel >= 1.5.0
 BuildRequires: sqlite-devel >= 3.6
 BuildRequires: libcap-devel >= 2.16