Remove obsolete Group tag

References: https://fedoraproject.org/wiki/Changes/Remove_Group_Tag

libyubikey.spec

@@ -3,7 +3,6 @@ Version:        1.13
 Release:        8%{?dist}
 Summary:        C library for decrypting and parsing Yubikey One-time passwords
 
-Group:          Development/Libraries
 License:        BSD
 URL:            http://opensource.yubico.com/yubico-c
 Source0:        http://opensource.yubico.com/yubico-c/releases/%{name}-%{version}.tar.gz
@@ -15,7 +14,6 @@ authentication device, the Yubikey.
 
 %package devel
 Summary:        Development files for libyubikey
-Group:          Development/Libraries
 Requires:       %{name} = %{version}-%{release}
 
 %description devel