Announcement: 3.4-asan is removed and replaced by asan-release

[eregon]

We want to keep at most 2 ASAN builds of CRuby:

• asan, which is ruby-head + ASAN
• asan-release, which is ruby (latest release) + ASAN

i.e. we cannot afford to keep more ASAN builds, they are already slow to build, not tested in CRuby upstream and so tend to break somewhat frequently.

So 3.4-asan is removed, and asan-release is now ruby-4.0.0 + ASAN since the latest release is 4.0.0.

TLDR:

     - uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 3.4-asan
+        ruby-version: asan-release

if you were using 3.4-asan (it seems very few people do according to download stats).

See ruby/ruby-dev-builder#15 (comment) for context.

This is not considered a breaking change giving the highly experimental nature of ASAN builds (not even tested in ruby/ruby CI).

Related commit: b90be12