Stop mentioning beta.mamba.pm (#688)

* Stop mentioning beta.mamba.pm

* Oups

Author: martinRenou

docs/environment.yml

@@ -1,6 +1,6 @@
 name: xeus-python-kernel-docs
 channels:
-  - https://repo.mamba.pm/emscripten-forge
+  - https://prefix.dev/emscripten-forge-dev
   - conda-forge
 dependencies:
   - xeus-python

docs/jupyterlite/configuration.md

@@ -13,7 +13,7 @@ Say you want to install `NumPy`, `Matplotlib` and `ipycanvas`, it can be done by
 ```yaml
 name: xeus-python-kernel
 channels:
-  - https://repo.mamba.pm/emscripten-forge
+  - https://prefix.dev/emscripten-forge-dev
   - conda-forge
 dependencies:
   - numpy
@@ -72,7 +72,7 @@ For example, if you were to install `ipycanvas` from PyPI, you would need to ins
 ```yaml
 name: xeus-python-kernel
 channels:
-  - https://repo.mamba.pm/emscripten-forge
+  - https://prefix.dev/emscripten-forge-dev
   - conda-forge
 dependencies:
   - numpy
@@ -88,7 +88,7 @@ a jupyterlite deployment in your Package documentation, allowing to test the ver
 ```yaml
 name: xeus-python-kernel
 channels:
-  - https://repo.mamba.pm/emscripten-forge
+  - https://prefix.dev/emscripten-forge-dev
   - conda-forge
 dependencies:
   - pip: