chore: also support diffpy.apps entry point

Author: ycexiao

pyproject.toml

@@ -51,6 +51,7 @@ exclude = []  # exclude packages matching these glob patterns (empty by default)
 namespaces = false  # to disable scanning PEP 420 namespaces (true by default)
 
 [project.scripts]
+"diffpy.apps" = "diffpy.apps.apps:main"
 "diffpy.app" = "diffpy.apps.apps:main"
 
 [tool.setuptools.dynamic]

src/diffpy/apps/apps.py

@@ -29,8 +29,8 @@ def main():
 
     parser.add_argument(
         "--version",
-        action="store_true",
-        help="Show the program's version number and exit",
+        action="version",
+        version=f"diffpy.apps {__version__}",
     )
     apps_parsers = parser.add_subparsers(
         title="Available applications",