minor #12641 Update MySQL column type definition (jbroutier)

This PR was submitted for the 4.4 branch but it was merged into the 3.4 branch instead (closes #12641).

Discussion
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Update MySQL column type definition

Update 4.4 documentation.

Commits
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8cd2e75 Update MySQL column type definition

Author: xabbuh

doctrine/pdo_session_storage.rst

@@ -254,7 +254,7 @@ MySQL
         `sess_id` VARCHAR(128) NOT NULL PRIMARY KEY,
         `sess_data` BLOB NOT NULL,
         `sess_time` INTEGER UNSIGNED NOT NULL,
-        `sess_lifetime` MEDIUMINT NOT NULL
+        `sess_lifetime` INTEGER UNSIGNED NOT NULL
     ) COLLATE utf8mb4_bin, ENGINE = InnoDB;
 
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