Use more active language

Original idea by @hedsnz with adjustments

Author: hartwork

Doc/library/xml.rst

@@ -65,8 +65,8 @@ connections.
 Expat versions lower than 2.7.2 may be vulnerable to the "billion laughs",
 "quadratic blowup" and "large tokens" vulnerabilities, or to disproportional
 use of dynamic memory.
-Python bundles a copy of Expat, and whether the bundled or a system-wide Expat
-is being used by Python, depends on how the Python interpreter
+Python bundles a copy of Expat, and whether Python uses the bundled or a
+system-wide Expat, depends on how the Python interpreter
 :option:`has been configured <--with-system-expat>` in your environment.
 Python may be vulnerable if it uses such older versions of Expat.
 Check :const:`!pyexpat.EXPAT_VERSION`.