Bump to v0.4.0

Author: lululxvi

setup.py

@@ -11,14 +11,14 @@
 
 setup(
     name="DeepXDE",
-    version="0.3.0",
+    version="0.4.0",
     description="Deep learning library for solving differential equations",
     long_description=long_description,
     long_description_content_type="text/markdown",
     author="Lu Lu",
     author_email="[email protected]",
     url="https://github.com/lululxvi/deepxde",
-    download_url="https://github.com/lululxvi/deepxde/tarball/v0.3.0",
+    download_url="https://github.com/lululxvi/deepxde/tarball/v0.4.0",
     license="Apache-2.0",
     install_requires=install_requires,
     classifiers=[