Change license from Apache to LGPL

CITATION.cff

@@ -29,4 +29,4 @@ identifiers:
     value: 10.1137/19M1274067
 repository-code: 'https://github.com/lululxvi/deepxde'
 url: 'https://deepxde.readthedocs.io'
-license: Apache-2.0
+license: LGPL-2.1

README.md

@@ -7,7 +7,7 @@
 [![PyPI Downloads](https://pepy.tech/badge/deepxde)](https://pepy.tech/project/deepxde)
 [![Conda Version](https://anaconda.org/conda-forge/deepxde/badges/version.svg)](https://anaconda.org/conda-forge/deepxde)
 [![Conda Downloads](https://img.shields.io/conda/dn/conda-forge/deepxde.svg)](https://anaconda.org/conda-forge/deepxde)
-[![License](https://img.shields.io/badge/license-Apache%202.0-blue.svg)](https://github.com/lululxvi/deepxde/blob/master/LICENSE)
+[![License](https://img.shields.io/github/license/lululxvi/deepxde)](https://github.com/lululxvi/deepxde/blob/master/LICENSE)
 
 [**Voting on whether we should have a Slack channel for discussion.**](https://github.com/lululxvi/deepxde/issues/371)
 
@@ -133,4 +133,4 @@ DeepXDE is currently maintained by [Lu Group](https://lu.seas.upenn.edu) at [Uni
 
 ## License
 
-[Apache license 2.0](https://github.com/lululxvi/deepxde/blob/master/LICENSE)
+[LGPL-2.1 License](https://github.com/lululxvi/deepxde/blob/master/LICENSE)

setup.py

@@ -39,33 +39,28 @@ def get_version(rel_path: str) -> str:
     author_email="[email protected]",
     url="https://github.com/lululxvi/deepxde",
     download_url="https://github.com/lululxvi/deepxde/tarball/v" + version,
-    license="Apache-2.0",
+    license="LGPL-2.1",
     install_requires=install_requires,
     classifiers=[
         "Development Status :: 4 - Beta",
-        "Intended Audience :: Developers",
-        "Intended Audience :: Education",
         "Intended Audience :: Science/Research",
-        "License :: OSI Approved :: Apache Software License",
-        "Programming Language :: Python :: 3",
+        "License :: OSI Approved :: GNU Lesser General Public License v2 (LGPLv2)",
+        "Programming Language :: Python :: 3 :: Only",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
         "Topic :: Scientific/Engineering",
         "Topic :: Scientific/Engineering :: Artificial Intelligence",
         "Topic :: Scientific/Engineering :: Mathematics",
-        "Topic :: Scientific/Engineering :: Physics",
-        "Topic :: Software Development :: Libraries",
-        "Topic :: Software Development :: Libraries :: Python Modules",
     ],
     keywords=[
-        "Deep Learning",
-        "Machine Learning",
-        "Neural Networks",
         "Scientific machine learning",
+        "Machine learning",
+        "Deep learning",
+        "Neural networks",
         "Scientific computing",
         "Differential equations",
-        "PDE solver",
+        "Physics-informed neural networks",
     ],
     packages=find_packages(),
     include_package_data=True,