Fix can't insert float into MySQL with PHP 7.3

When inserting a float value into MySQL via the Illuminate\Database package when using at least PHP 7.3, the value is converted to an int.

The bug has been reported a few times before:

* laravel#30435
* illuminate/database#246

PR laravel#16069 introduced logic to the MySQLConnection that cast floats to ints to address a comparison problem with JSON columns, which was reported in issue laravel#16069. This does not seem to cause a problem with PHP 7.1 and below but causes the float to lose it's decimal places when using PHP 7.3. I have not tested with PHP 7.2.

Given we have the following MySQL table:

```
CREATE TABLE `zip_codes` (
  `zip_code` varchar(255) NOT NULL,
  `latitude` decimal(15,10) NOT NULL,
  `longitude` decimal(15,10) NOT NULL
)
```

When we execute the following using Artisan Tinker:

```php
DB::table('zip_codes')->delete();

// Using the same values
$lat = -0.2;
$lon = 0;
$sql = 'INSERT INTO zip_codes (latitude, longitude, zip_code) VALUES (:lat, :long, :zip)';

// We insert the first by using PDO directly
$values = [':lat' => $lat, ':long' => $lon, ':zip' => 1];
DB::connection()->getPdo()->prepare($sql)->execute($values);

// Then the second by using Eloquent
DB::table('zip_codes')->insert(['latitude' => $lat, 'longitude' => $lon, 'zip_code' => 2]);

// Then pull them both.
DB::table('zip_codes')->get();
```

Then we should see both records with -0.2 as the latitude. But only the first has the value, and the second row is zero.

src/Illuminate/Database/MySqlConnection.php

@@ -7,7 +7,6 @@
 use Illuminate\Database\Query\Processors\MySqlProcessor;
 use Illuminate\Database\Schema\Grammars\MySqlGrammar as SchemaGrammar;
 use Illuminate\Database\Schema\MySqlBuilder;
-use PDO;
 
 class MySqlConnection extends Connection
 {
@@ -64,21 +63,4 @@ protected function getDoctrineDriver()
     {
         return new DoctrineDriver;
     }
-
-    /**
-     * Bind values to their parameters in the given statement.
-     *
-     * @param  \PDOStatement  $statement
-     * @param  array  $bindings
-     * @return void
-     */
-    public function bindValues($statement, $bindings)
-    {
-        foreach ($bindings as $key => $value) {
-            $statement->bindValue(
-                is_string($key) ? $key : $key + 1, $value,
-                is_int($value) || is_float($value) ? PDO::PARAM_INT : PDO::PARAM_STR
-            );
-        }
-    }
 }