Remove obsolete Group tag

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

libmatroska.spec

@@ -3,7 +3,6 @@ Name:		libmatroska
 Version:	1.4.9
 Release:	2%{?dist}
 License:	LGPLv2+
-Group:		System Environment/Libraries
 URL:		https://www.matroska.org/
 Source0:	https://dl.matroska.org/downloads/%{name}/%{name}-%{version}.tar.xz
 BuildRequires:	cmake
@@ -19,7 +18,6 @@ is usually found as .mkv files (matroska video) and .mka files
 
 %package	devel
 Summary:	Matroska container format library development files
-Group:		Development/Libraries
 Requires:	%{name}%{_isa} = %{version}-%{release}
 Requires:	cmake-filesystem
 Requires:	libebml-devel >= 1.3.6