thunderbird: Update version from 52.2.1 to 52.3.0

[Release notes][1]:

> Version 52.3.0, first offered to Release channel users on August 16,
> 2017

> ### What’s New ###
>
> *   Fixed: [Various security fixes][2]
> *   Fixed: Large attachments taking a long time to open under some
>     circumstances
> *   Fixed: No authorisation prompt displayed when inserting image into
>     email body although image URL requires authentication
> *   Fixed: Selected text from another message sometimes included in a
>     reply
> *   Fixed: Inline images not scaled to fit when printing
> *   Fixed: Message disposition flag (replied / forwarded) lost when
>     reply or forwarded message was stored as draft and draft was sent
>     later
> *   Fixed: Deleting message from the POP3 server not working when
>     maildir storage was used
> *   Fixed: Unwanted inline images shown in rogue SPAM messages

> ### Known Issues ###
>
> *   unresolved: Multiple requests for master password when GMail
>     OAuth2 is enabled
> *   unresolved: On Windows, "Send to > Mail recipient" does not work.
>     Workaround: Install the Microsoft Visual Studio 2015
>     redistributable runtime library or the Universal C Runtime for
>     Windows Server.

[1]: https://www.mozilla.org/en-US/thunderbird/52.3.0/releasenotes/
[2]: https://www.mozilla.org/en-US/security/known-vulnerabilities/thunderbird/#thunderbird52.3
[3]: https://www.mozilla.org/en-US/security/advisories/mfsa2017-20/

thunderbird.be0

@@ -2,7 +2,7 @@
 
 #export BEE_TMP_TMPDIR=/dev/shm BEE_TMP_BUILDROOT=/dev/shm/bee-root BEE_MAKEFLAGS='-j80'
 
-# BEE_VERSION thunderbird-52.2.1-0
+# BEE_VERSION thunderbird-52.3.0-0
 
 SRCURL[0]="https://ftp.mozilla.org/pub/thunderbird/releases/${PKGVERSION}/source/thunderbird-${PKGVERSION}.source.tar.xz"