[BUGFIX] Provide an error message if ext version is not found

The translation key "msg.version_not_found" is missing.
Add it to the translation file.

Change-Id: I2b7c5c8633465c97d1369d0e2326ff8f9b265b33
Resolves: #59236
Reviewed-on: http://review.typo3.org/31318
Reviewed-by: Philipp Gampe <philipp.gampe@typo3.org>
Tested-by: Philipp Gampe <philipp.gampe@typo3.org>