Support releasing on macOS. (#16266)

changelog.d/16266.misc

@@ -0,0 +1 @@
+Update the release script to work on macOS.

scripts-dev/release.py

@@ -244,6 +244,12 @@ def _prepare() -> None:
     else:
         debian_version = new_version
 
+    if sys.platform == "darwin":
+        run_until_successful(
+            f"docker run --rm -v .:/synapse ubuntu:latest /synapse/scripts-dev/docker_update_debian_changelog.sh {new_version}",
+            shell=True,
+        )
+    else:
         run_until_successful(
             f'dch -M -v {debian_version} "New Synapse release {new_version}."',
             shell=True,
@@ -566,14 +572,22 @@ def _notify(message: str) -> None:
     # for this.
     click.echo(f"\a{message}")
 
+    app_name = "Synapse Release Script"
+
     # Try and run notify-send, but don't raise an Exception if this fails
     # (This is best-effort)
-    # TODO Support other platforms?
+    if sys.platform == "darwin":
+        # See https://developer.apple.com/library/archive/documentation/AppleScript/Conceptual/AppleScriptLangGuide/reference/ASLR_cmds.html#//apple_ref/doc/uid/TP40000983-CH216-SW224
+        subprocess.run(
+            f"""osascript -e 'display notification "{message}" with title "{app_name}"'""",
+            shell=True,
+        )
+    else:
         subprocess.run(
             [
                 "notify-send",
                 "--app-name",
-            "Synapse Release Script",
+                app_name,
                 "--expire-time",
                 "3600000",
                 message,