minor #11844 [HttpClient] Fix code block (andreia)

This PR was submitted for the master branch but it was merged into the 4.4 branch instead (closes #11844).

Discussion
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[HttpClient] Fix code block

Commits
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9878335 [HttpClient] Fix code block

Author: javiereguiluz

components/http_client.rst

@@ -713,7 +713,7 @@ relevant parts of PSR-17, ``HttplugClient`` also implements the factory methods
 defined in the related ``php-http/message-factory`` package.
 
 Internally, the implementation relies on the ``Psr18Client``, so that the
-``psr/http-client`` package is needed to use this class::
+``psr/http-client`` package is needed to use this class:
 
 .. code-block:: terminal