Fix tests of older Laravel versions

Author: peterfox

src/CockroachDbConnection.php

@@ -46,7 +46,7 @@ public function getSchemaBuilder(): DbBuilder
      */
     protected function getDefaultSchemaGrammar(): BaseGrammar
     {
-        return $this->withTablePrefix((new SchemaGrammar())->setConnection($this));
+        return $this->withTablePrefix($this->setConnection(new SchemaGrammar());
     }
 
     /**
@@ -77,4 +77,16 @@ protected function getDoctrineDriver()
     {
         return new PostgresDriver();
     }
+
+    /**
+     * Required to set the connection. This isn't compatible with older Laravel versions
+     */
+    protected function setConnection(BaseGrammar $grammar): BaseGrammar
+    {
+        if (method_exists($grammar, 'setConnection')) {
+            return $grammar->setConnection($this);
+        }
+
+        return $grammar;
+    }
 }