Bump version for release.

NEWS

@@ -1,6 +1,6 @@
-1.9.1.dev0
+1.9.1
  * #928: Fix the user runtime directory location on macOS (and possibly Cygwin).
- * #930: Fix error with multiple systemd credentials when no credentials are configured.
+ * #930: Fix an error with the sample systemd service when no credentials are configured.
  * #931: Fix an error when implicitly upgrading the check state directory from ~/.borgmatic to
    ~/.local/state/borgmatic across filesystems.
 

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "borgmatic"
-version = "1.9.1.dev0"
+version = "1.9.1"
 authors = [
   { name="Dan Helfman", email="witten@torsion.org" },
 ]