TYPO3 queries information of translations.
The fix adds database indices which are also applied for tt_content
by TYPO3 itself.
This fixes slow loading times of the list module.
- Extend CI to test everything against PHP 7.3
- Update composer to allow installation with PHP 7.3
- Remove dependency checker, install loosely within CI to get compatible
version with actual PHP version.
- Adjust CI to use PHP compatible MySQL versions.
Relates: #69
Provide database index for widgets which is used by widget queries to
fetch data way faster, e.g. 0.1 instead of > 5 seconds in one concrete
project.
Relates: #63
