Update README with updated runners

[skip ci]

Signed-off-by: Jason Frey <[email protected]>

Author: Fryguy

README.md

@@ -84,7 +84,7 @@ The action works on these [GitHub-hosted runners](https://docs.github.com/en/act
 | OS      | Supported        |
 | ------- | ---------------- |
 | Ubuntu  | `ubuntu-24.04`, `ubuntu-22.04` (`ubuntu-latest`), `ubuntu-20.04` |
-| macOS   | `macos-14` (`macos-latest`), `macos-13`, `macos-12` |
+| macOS   | `macos-15`, `macos-14` (`macos-latest`), `macos-13` |
 | Windows | `windows-2022` (`windows-latest`), `windows-2019` |
 
 ## Contributing