CI (Linux): fix musl build

Author: CarterLi

CMakeLists.txt

@@ -1961,11 +1961,13 @@ if(LINUX)
         endif()
     endif()
 
-    find_program(HAVE_RPMBUILD "rpmbuild")
-    if(HAVE_RPMBUILD)
-        set(CPACK_GENERATOR "${CPACK_GENERATOR};RPM")
+    if(NOT IS_MUSL)
+        find_program(HAVE_RPMBUILD "rpmbuild")
+        if(HAVE_RPMBUILD)
+            set(CPACK_GENERATOR "${CPACK_GENERATOR};RPM")
 
-        set(CPACK_RPM_PACKAGE_LICENSE "MIT")
+            set(CPACK_RPM_PACKAGE_LICENSE "MIT")
+        endif()
     endif()
 elseif(FreeBSD)
     set(CPACK_FREEBSD_PACKAGE_LICENSE "MIT")