PHP supports it natively since 5.4.

acaaa76 also started to use it,
presumably to fix sites that were incorrectly declaring `deflate`
method when they were using `gzip`.

And since we require PHP 7.2, and the zlib extension is already
mandatory for the `gzinflate` and `gzuncompress` functions,
let’s also remove the `funcion_exists` check.

When a regex contains a capture group within another capture group followed by `?`,
and the outer group is not matched, the resulting matched text for both groups will be an empty string. (1)
Or, if there are no further matched capture groups, the indices for the groups will be simply omitted from the `$matches` array. (2)

We want missing components of the URI to be `null` so we had a conditionals for the aforementioned matches.

As of PHP 7.2, we can just use `PREG_UNMATCHED_AS_NULL` to get `null`s in the case (1):
https://www.php.net/manual/en/function.preg-match.php#refsect1-function.preg-match-parameters

If we raised minimum PHP version to 7.4, we would not even need the `isset` to handle (2) because from that version onward, the flag also disables the omission of tail unmatched groups:
https://www.php.net/manual/en/migration74.incompatible.php#migration74.incompatible.pcre

Switch the optional outer capture groups (1, 3, 6 and 8) to anonymous ones now that we are no longer using them for anything.

Looks like this has been incorrect since 5bf1814

Revealed by PHPStan level 8.

* Builds against PHP 8.4 are no longer allowed to fail.

Ref: https://www.php.net/releases/8.4/en.php