message: Fix typo in bors.toml
diff: @@ -5,8 +5,8 @@ status = [
  "Test on linux-aarch64",
  "Test on macos",
  "Test on windows",
  - "Test cross-compile on Linux",
  - "Test cross-compile on Mac",
  + "Test cross-compile on linux",
  + "Test cross-compile on macos",
  ]
  required_approvals = 1
  timeout_sec = 7200
  