chore(mge/version): change dev version to 1.3

GitOrigin-RevId: b5e5327a46675f73d1cb600712c8584b2b761769

imperative/python/megengine/version.py

@@ -6,5 +6,5 @@
 # Unless required by applicable law or agreed to in writing,
 # software distributed under the License is distributed on an
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-__version__ = "1.2.0.dev"
+__version__ = "1.3.0.dev"