Using ${var} in strings is deprecated, use {$var} instead

In php8.2
https://wiki.php.net/rfc/deprecate_dollar_brace_string_interpolation

Change-Id: Ieaf5a620efd04ee46598577a9d1905c62c2b052e

src/SecurityCheckPlugin.php

@@ -590,7 +590,7 @@ public static function parseTaintLine( string $line ): ?array {
 		$types = '(?P<type>htmlnoent|html|sql|shell|serialize|custom1|'
 			. 'custom2|code|path|regex|sql_numkey|escaped|none|tainted)';
 		$prefixes = '(?P<prefix>escapes|onlysafefor|exec)';
-		$taintExpr = "(?P<taint>(?:${prefixes}_)?$types|array_ok|allow_override)";
+		$taintExpr = "(?P<taint>(?:{$prefixes}_)?$types|array_ok|allow_override)";
 
 		$filteredLine = preg_replace( "/((?:$taintExpr,? *)+)(?: .*)?$/", '$1', $line );
 		$taints = explode( ',', strtolower( $filteredLine ) );