New version 5.1.2 of Joomla Update Component stand-alone package

[richard67]

See CMS PR joomla/joomla-cms#43695 .

Zip standalone package attached: com_joomlaupdate-5.1.2.zip

The targetplatform version for the new version of the component is 5.1.[012], so that the update will be found on CMS versions 5.10, 5.1.1 and 5.1.2-dev. The latter might be current nightlies. When 5.1.2 will be stable there will not be an update found anymore despite of that targetplatform version because the component's version will be already up to date.

I've verified that there were no changes on the update component between 5.1.0 and current 5.1.2-dev, so the package provided here should work on all these CMS versions.

To be done:

• Adjust <infourl> to the release announcement for Joomla 5.1.2 - this needs to know the article ID because that's part of the URL.
• Check and if necessary correct or remove some of the 3 download URLs or download sources.
• Maybe create package for the component again from the final CMS package so that the file modification times are the same in the CMS package and the component's package, and update the sha checksums.

As long as that is not clarified or done I will leave this PR in draft status, but it can already be reviewed if everything else is right.

[richard67]

Meanwhile it has been checked that the update to 5.1.2 can be provided to both update channels so it does not need a separate update for the update component.