All Windows jobs failing to download doxygen from sourceforge

This started yesterday in #7006 and #7007
Every Windows job including 4 retries is failing:

```
Run md c:\projects\install
md c:\projects\install
(New-Object System.Net.WebClient).DownloadFile("https://github.com/ninja-build/ninja/releases/download/v1.10.[2](https://github.com/DynamoRIO/dynamorio/actions/runs/11060833652/job/30734710596?pr=7007#step:5:2)/ninja-win.zip", "c:\projects\install\ninja.zip")
(New-Object System.Net.WebClient).DownloadFile("https://sourceforge.net/projects/doxygen/files/rel-1.8.19/doxygen-1.8.19.windows.x64.bin.zip", "c:\projects\install\doxygen.zip")
shell: C:\Windows\System[3](https://github.com/DynamoRIO/dynamorio/actions/runs/11060833652/job/30734710596?pr=7007#step:5:3)2\WindowsPowerShell\v1.0\powershell.EXE -command ". '{0}'"

Directory: C:\projects

Mode LastWriteTime Length Name
---- ------------- ------ ----
d----- 9/26/202[4](https://github.com/DynamoRIO/dynamorio/actions/runs/11060833652/job/30734710596?pr=7007#step:5:4) 11:15 PM install
Exception calling "DownloadFile" with "2" argument(s): "The remote server returned an error: (403) Forbidden."
At D:\a\_temp\dbaf31b[5](https://github.com/DynamoRIO/dynamorio/actions/runs/11060833652/job/30734710596?pr=7007#step:5:5)-ffc6-4740-854c-2956bb5056a5.ps1:4 char:1
+ (New-Object System.Net.WebClient).DownloadFile("https://sourceforge.n ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], ParentContainsErrorRecordException
+ FullyQualifiedErrorId : WebException

Error: Process completed with exit code 1.
```

#4643 switched our doxygen download to sourceforge 4 years ago and has worked ever since: until now.

The link works manually though: in a browser, or `wget https://sourceforge.net/projects/doxygen/files/rel-1.8.19/doxygen-1.8.19.windows.x64.bin.zip`. As @edeiana points out at https://github.com/DynamoRIO/dynamorio/pull/7007#issuecomment-2378182795 there are redirection so maybe that is part of the problem: but the Forbidden error is odd.