minor #15373 Remove master wording (jschaedl)

This PR was submitted for the 5.2 branch but it was merged into the 4.4 branch instead.

Discussion
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Remove master wording

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Commits
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f03863d Remove master wording

Author: javiereguiluz

contributing/code/conventions.rst

@@ -223,7 +223,7 @@ Removing Deprecated Code
 ------------------------
 
 Removing deprecated code can only be done once every 2 years, on the next major version of the
-impacted component (``master`` branch).
+impacted component (``6.0`` branch).
 
 When removing deprecated code, the consequences of the deprecation must be added to the ``CHANGELOG.md`` file
 of the impacted component: