gh-145177: Upgrade to Emscripten 6.0.8

[hoodmane]

• Issue: Emscripten buildbot: Support multiple Emscripten versions #145177

[freakboy3742]

👍

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 CentOS9 Refleaks 3.x (tier-1) has failed when building commit 8e3271d.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/853/builds/4169) and take a look at the build logs.
4. Check if the failure is related to this commit (8e3271d) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/853/builds/4169

Summary of the results of the build (if available):

==

Click to see traceback logs

Note: switching to '8e3271d3101540f8662745730a1a04635def502a'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:

  git switch -c <new-branch-name>

Or undo this operation with:

  git switch -

Turn off this advice by setting config variable advice.detachedHead to false

HEAD is now at 8e3271d31015 gh-145177: Upgrade to Emscripten 6.0.8 (#156334)
Switched to and reset branch 'main'

make: *** [Makefile:2476: buildbottest] Error 3