Bump macOS GitHub CI runner version

[knelli2]

Proposed changes

Currently just using this draft PR to see if this works since macos-11 will be deprecated at the end of next month. macos-13 is the last version still on intel chips. macos-14 and macos-latest are on M1 chips

Upgrade instructions

Code review checklist

• The code is documented and the documentation renders correctly. Run
  make doc to generate the documentation locally into BUILD_DIR/docs/html.
  Then open index.html.
• The code follows the stylistic and code quality guidelines listed in the
  code review guide.
• The PR lists upgrade instructions and is labeled bugfix or
  new feature if appropriate.

Further comments

[nilsvu]

See also commits in #5973

[knelli2]

Ok @sxs-collaboration/spectre-core-devs I finally got this to work. These are the minimal changes to get macOS CI back up and running. I'd like to do this first before we do anything more fancy like in #5973.

[nilsdeppe]

LGTM. I think macOS has been doing weird things with signals. E.g. FPEs raise sigill instead.

Separate: we should use 4 cores on Linux too since they seem to have increased what's available

[wthrowe]

Sounds like the test might actually work as intended on Mac but not Linux.

[knelli2]

I think mac does something different when handling signals vs exceptions. Because in the catch docs it says all the CHECK_(NO)THROW* macros handle exceptions and doesn't mention signals. So my best guess is that on linux this test works as intended because CATCH_THROWS_WITH doesn't catch the SIGSEGV, so the test "fails" and our output test catches that and reports that the test actually passes. However, on mac, somehow CHECK_THROWS_WITH catches SIGSEGV so the test "succeeds" and then our output test actually fails because no message was printed.

[wthrowe]

We throw an exception in the signal handler.

[knelli2]

Oh... Then I have no clue 🤷🏻