Improve auto-update hash extraction regex

- Match only space and tab (\x20\t) instead of all whitespaces (\s)
- Match only supported hash length (32 for md5 until 128 for sha512)
- Ignores everything before the filename
- Fixes a small bug where the last bit matched first digits from the next line but was not an issue because of non-capture group

lib/autoupdate.ps1

@@ -55,7 +55,7 @@ function find_hash_in_textfile([String] $url, [String] $basename, [String] $rege
 
     # find hash with filename in $hashfile (will be overridden by $regex)
     if ($hash.Length -eq 0 -and $regex.Length -eq 0) {
-        $filenameRegex = "([a-fA-F0-9]+)\s+(?:\.\/|\*)?(?:`$basename)(\s[\d]+)?"
+        $filenameRegex = "([a-fA-F0-9]{32,128})[\x20\t]+.*`$basename(?:[\x20\t]+\d+)?"
         $filenameRegex = substitute $filenameRegex @{'$basename' = [regex]::Escape($basename)}
         if ($hashfile -match $filenameRegex) {
             $hash = $matches[1]