Bump plugin version to 3.2.1

A patch release for #131: the NGSI-LD link moved into Redmine's own export
list. No schema, API or settings change, so nothing to migrate.

doc/api.md says "Since version 3.2", which stays correct on the 3.2 line.

Author: dkastl

init.rb

@@ -8,7 +8,7 @@
   author_url 'https://github.com/dkastl'
   url 'https://github.com/gtt-project/redmine_gtt_fiware'
   description 'Adds FIWARE integration capabilities for GTT projects'
-  version '3.2.0'
+  version '3.2.1'
 
   # Specify the minimum required Redmine version
   requires_redmine :version_or_higher => '6.0.0'