Add PHP 7.4 support (#464)

* Add PHP 7.4 to build matrix

* DB fix

* YAML parser fix in test data

* Show versions

* Package updates

* Track used ICAOs

* 7.4 METAR parsing fix

* METAR parser fix

* Formatting

* Add meters to response units

* Call instance for unit conversion

* Return value

* Catch exception for unknown quantity

* Comment fix

* Formatting

* METAR parsing fixes on PHP 7.4

* Package updates

* More random airport ID

* More random airport ID

* Properly disable toolbar

* Semver written out to version file

* Use dev as default identifier

app/Support/Units/Distance.php

@@ -8,6 +8,7 @@ use PhpUnitsOfMeasure\PhysicalQuantity\Length;
 class Distance extends Unit
 {
     public $responseUnits = [
+        'm',
         'km',
         'mi',
         'nmi',