Bump version for release.

NEWS

@@ -1,4 +1,4 @@
-1.9.10.dev0
+1.9.10
  * #966: Add a "!credential" tag for loading systemd credentials into borgmatic configuration
    files. See the documentation for more information:
    https://torsion.org/borgmatic/docs/how-to/provide-your-passwords/

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "borgmatic"
-version = "1.9.10.dev0"
+version = "1.9.10"
 authors = [
   { name="Dan Helfman", email="witten@torsion.org" },
 ]