[BUGFIX] Allow to set replyTo email address in ext:felogin

If the TypoScript variable `plugin.tx_felogin_pi1.replyTo` was set to
an email address, it triggered the following error:
`Symfony\\Component\\Mime\\Exception\\InvalidArgumentException: An address
can be an instance of Address or a string (\"array\") given)`

Releases: master
Resolves: #91458
Change-Id: I4179d42025d0373cd1d7c0938a83ec0c90e25465
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64559


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Susanne Moog <look@susi.dev>
Reviewed-by: Guido Schmechel <guido.schmechel@brandung.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>