Use proper types in tests

[franmomu]

This PR tries to fix some PHPStan findings in level 5, in this case about calling some method with wrong types.

Elastica/src/Aggregation/GapPolicyInterface.php

Lines 15 to 35 in c0bcdb3

	/**
	* Treats missing data as if the bucket does not exist. It will skip the bucket and continue calculating using the next available value.
	*/
	public const SKIP = 'skip';
	/**
	* Will replace missing values with a zero (0) and pipeline aggregation computation will proceed as normal.
	*/
	public const INSERT_ZEROS = 'insert_zeros';
	/**
	* Is similar to skip, except if the metric provides a non-null, non-NaN value this value is used, otherwise the empty bucket is skipped.
	*/
	public const KEEP_VALUES = 'keep_values';
	/**
	* Set the gap policy for this aggregation.
	*
	* @return $this
	*/
	public function setGapPolicy(string $gapPolicy);

setGapPolicy expects a string which is one of the policies.

Elastica/src/Document.php

Line 208 in c0bcdb3

public function setDocAsUpsert(bool $value): self

Document:: setDocAsUpsert() expects a bool

Elastica/src/Connection.php

Lines 76 to 83 in c0bcdb3

	/**
	* @param int $port
	*
	* @return $this
	*/
	public function setPort($port)
	{
	return $this->setParam('port', (int) $port);

Connection::setPort() expects an int and also the default value (9200) is stored as int, internally it casts the value to int, but IMO we should stick to int since it represents a port.