Replace deprecated string interpolation usage

[flavioheleno]

This PR replaces the now deprecated (as of PHP 8.2) ${var} usage in string interpolation by {$var}.
Note that this change is backwards compatible with previous versions of PHP.

Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /usr/src/app/tests/HTML5DOMDocumentTest.php on line 67
Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /usr/src/app/tests/HTML5DOMDocumentTest.php on line 74
Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /usr/src/app/src/voku/helper/SimpleHtmlDom.php on line 508
Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /usr/src/app/src/voku/helper/SimpleHtmlDom.php on line 520
Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /usr/src/app/src/voku/helper/SimpleHtmlDom.php on line 555
Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /usr/src/app/src/voku/helper/SimpleXmlDom.php on line 458
Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /usr/src/app/src/voku/helper/SimpleXmlDom.php on line 470
Deprecated: Using ${var} in strings is deprecated, use {$var} instead in /usr/src/app/src/voku/helper/SimpleXmlDom.php on line 505

Reference: https://wiki.php.net/rfc/deprecate_dollar_brace_string_interpolation

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[sonarqubecloud]

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[phpfui]

This PR looks good to me. Can we get a new release that will support PHP 8.2 without depreciations? Also see PR #93

Thanks!

[dyaskur]

LGTM too, and I need this update too

[phpfui]

Check out PR #93 while you are at it. This is a more serious issue, as the library does not work on 8.2.

[dyaskur]

Actually I dont know about #93 issue, I used 8.2 on production and it work as expected. Just have deprecated warning like on this PR.

But yeah, I hope that will be merged too. Maybe in the future I use the feature that has issue on 8.2.

[phpfui]

This PR is good to merge for PHP 8.2 and does not affect older versions.

[voku]

Thanks, version 4.8.8 is released with this fix.