Locked the PHP_CodeSniffer version to 3.5 for better compatibility with PHP 7.4

PingableConnection and ServerInfoAwareConnection now extend Connection

VersionAwarePlatformDriver now extends Driver

Manually merge 2.10 into master

Switched from PHPBrew-based configuration to the Docker-based

As per the support response, continuousphp switched to building their containers based on the official images from PHP.

Remove temporary SQLite file on teardown

Update deprecation messages to refer to DBAL

Fix of branch names for doctrine website config

Fix upgrade comment about MariaDB

Generally advising to upgrade MariaDB to PostgreSQL isn't helpful ;)

Add .doctrine-project.json to .gitattributes

Replace DefaultTypes with Types in type constant deprecation annotations

Remove phpunit-bridge specific annotations

The phpunit-bridge has been removed in #3643, so these no longer serve
any purpose. The tests themselves are kept since they check that there
is no crash when using an unknown option, and do not need a phpunit
assertion to do so.

Update releases documentation

`v2.10` is the `current` one now.

Fix branch-alias (master is now 3.0)

Merge all the work done so far for the 3.0.0 release into master

Drop db support for PostgreSQL 9.3 and MariaDB 10.0

Removed Driver::getDatabase() in favor of Connection::getDatabase()

Remove support for sharding and the Azure platform

Make sure that (VAR)CHAR column length is specified in characters, not bytes

Removed some unused code bits