package/mxml: bump to version 3.2

package/mxml: bump to version 3.2

The hash of the NOTICE file has changed due to the following minor update:

-Exceptions to the Apache 2.0 License:
-=====================================
+(Optional) Exceptions to the Apache 2.0 License:
+================================================

Also update hash file formatting (2 spaces)

See changelog https://github.com/michaelrsweet/mxml/releases/tag/v3.2

Signed-off-by: Pierre-Jean Texier <pjtexier@koncepto.io>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>