Stop calling xmlMemoryDump

This was used to check for memory leaks but could potentially create a
.memdump file. These days, there are better ways to check for memory
leaks.

python/tests/tstURI.py

@@ -38,4 +38,3 @@ if libxml2.debugMemory(1) == 0:
     print("OK")
 else:
     print("Memory leak %d bytes" % (libxml2.debugMemory(1)))
-    libxml2.dumpMemory()