Update macOS x86_64 wheel build CI runner to 10.13

Github actions has deprecated their macOS 10.12 CI runner and will be
removing it in December, 2024. We were using this macOS runner because
our target OS version for intel mac is 10.12. However, with this
enviornment being removed by Github we must upgrade to continue running
the jobs.

This commit does not bump the MACOSX_DEPLOYMENT_TARGET environment
variable (which is used to set the target OS version for intel macs)
though, because we should test if we can build it compatibility
mode from a newer version of macOS. If this fails then we can bump this
to 10.13 in a subsequent commit on this PR and add an upgrade release
note to document the change.

.github/workflows/wheels-build.yml

@@ -90,7 +90,7 @@ jobs:
         os:
           - ubuntu-latest
           # Used for the x86_64 builds.
-          - macos-12
+          - macos-13
           # Used for the ARM builds.
           - macos-14
           - windows-latest