Merge #11031

11031: minor: Set `MACOSX_DEPLOYMENT_TARGET` to 10.15 to improve compat r=lnicola a=lnicola

Since GitHub (and also us, explicitly) switched the `macos-latest` runners to 11, let's try to bring back support for 10.15.

Co-authored-by: Laurențiu Nicola <[email protected]>

Author: bors[bot]

.github/workflows/release.yaml

@@ -16,6 +16,7 @@ env:
   RUSTFLAGS: "-D warnings -W unreachable-pub"
   RUSTUP_MAX_RETRIES: 10
   FETCH_DEPTH: 0 # pull in the tags for the version string
+  MACOSX_DEPLOYMENT_TARGET: 10.15
 
 jobs:
   dist: