ci: simplify pixi commands in ReadTheDocs config

Removes explicit environment specification from pixi install/run commands
as it's no longer needed with the latest pixi version

Author: liblaf

template/.readthedocs.yaml.jinja

@@ -1,3 +1,4 @@
+# -*- mode: yaml; -*-
 # yaml-language-server: $schema=https://raw.githubusercontent.com/readthedocs/readthedocs.org/master/readthedocs/rtd_tests/fixtures/spec/v2/schema.json
 # This file is @generated by <https://github.com/liblaf/copier-python>.
 # DO NOT EDIT!
@@ -33,7 +34,7 @@ build:
 
     install:
       # {%- if package_manager == "pixi" %}
-      - pixi install --environment "docs"
+      - pixi install
       # {%- elif package_manager == "uv" %}
       - UV_PROJECT_ENVIRONMENT="$READTHEDOCS_VIRTUALENV_PATH" uv sync --all-extras --all-groups --link-mode copy
       # {%- endif %}
@@ -44,7 +45,7 @@ build:
     # {%- if package_manager == "pixi" %}
     build:
       html:
-        - pixi run --environment "docs" mkdocs build --site-dir "$READTHEDOCS_OUTPUT/html/"
+        - pixi run mkdocs build --site-dir "$READTHEDOCS_OUTPUT/html/"
     # {%- endif %}
 
 mkdocs: