Fix broken OpenAi links

Author: AntoinePrv

README.rst

@@ -27,7 +27,7 @@ in cooperation with a state-of-the-art Mixed Integer Linear Programming solver
 that acts as a controllable algorithm.
 
 The underlying solver used is `SCIP <https://scip.zib.de/>`_, and the user facing API is
-meant to mimic the `OpenAI Gym <https://gym.openai.com/>`_ API (as much as possible).
+meant to mimic the `OpenAI Gym <https://www.gymlibrary.dev/>`_ API (as much as possible).
 
 .. code-block:: python
 

docs/index.rst

@@ -38,7 +38,7 @@ picking the next variable to branch on. Ecole aims at exposing these algorithmic
 standard reinforcement learning API (agent / environment loop), in order to ease the exploration
 of new machine learning models and algorithms for learning data-driven policies.
 
-Ecole's interface is inspired from `OpenAI Gym <https://gym.openai.com/>`_ and will look
+Ecole's interface is inspired from `OpenAI Gym <https://www.gymlibrary.dev/>`_ and will look
 familiar to reinforcement learning praticionners.
 The state-of-the-art Mixed Integer Linear Programming solver that acts as a controllable
 algorithm inside Ecole is `SCIP <https://scip.zib.de/>`_.

libecole/include/ecole/environment/environment.hpp

@@ -28,7 +28,7 @@ namespace ecole::environment {
  * Environments are the main abstraction exposed by Ecole.
  * They characterise the Markov Decision Process task to solve.
  * The interface to environments is meant to be close to that of
- * [OpenAi Gym](https://gym.openai.com/), with some differences nontheless due to the
+ * [OpenAi Gym](https://www.gymlibrary.dev/), with some differences nontheless due to the
  * requirements of Ecole.
  *
  * @tparam Dynamics The ecole::environment::EnvironmentDynamics driving the initial state and transition of the