(feat) add --version to cli (#3924)

openhands/__init__.py

@@ -0,0 +1,28 @@
+def get_version():
+    try:
+        from importlib.metadata import PackageNotFoundError, version
+
+        try:
+            return version('openhands-ai')
+        except PackageNotFoundError:
+            pass
+    except ImportError:
+        pass
+
+    try:
+        from pkg_resources import DistributionNotFound, get_distribution
+
+        try:
+            return get_distribution('openhands-ai').version
+        except DistributionNotFound:
+            pass
+    except ImportError:
+        pass
+
+    return 'unknown'
+
+
+try:
+    __version__ = get_version()
+except Exception:
+    __version__ = 'unknown'