lib/ims: libxml2 is not needed - removed from cmake

(cherry picked from commit 11a609d06b527470c535a20866c48cafdedcb820)

src/lib/ims/CMakeLists.txt

@@ -1,4 +1,2 @@
-find_package(LibXml2 REQUIRED)
-
 file(GLOB SRC_FILES "*.c")
 target_sources(kamailio PUBLIC ${SRC_FILES})