Fix version number in language reference

Author: edoardopirovano

docs/codeql/ql-language-reference/ql-language-specification.rst

@@ -1333,7 +1333,7 @@ The values of a set literal expression are all the values of all the contained e
 
 Set literals are supported from release 2.1.0 of the CodeQL CLI, and release 1.24 of LGTM Enterprise.
 
-Since release 2.7.0 of the CodeQL CLI, and release 1.28 of LGTM Enterprise, a trailing comma is allowed in a set literal.
+Since release 2.7.1 of the CodeQL CLI, and release 1.28 of LGTM Enterprise, a trailing comma is allowed in a set literal.
 
 Disambiguation of expressions
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