PHP 7.4 fixes

- Fix `Model::activeAttributes()` to access array offset on value of non-string
- Fix incorrect decoding of default binary value for PostgreSQL
- Fix incorrect type-casting of reflection type to string

framework/base/Model.php

@@ -819,7 +819,7 @@ class Model extends Component implements StaticInstanceInterface, IteratorAggreg
         }
         $attributes = array_keys(array_flip($scenarios[$scenario]));
         foreach ($attributes as $i => $attribute) {
-            if ($attribute[0] === '!') {
+            if (strncmp($attribute, '!', 1) === 0) {
                 $attributes[$i] = substr($attribute, 1);
             }
         }