chore: Simplify 'pixi run' commands (#10)

* The run commands are properly defined in the environments and are unique,
  so the environment does not need to be specified with the --environment flag.

.github/workflows/ci.yml

@@ -30,4 +30,4 @@ jobs:
 
     - name: Test with pytest and coverage
       run: |
-        pixi run --environment test test
+        pixi run test

.github/workflows/lint.yaml

@@ -28,8 +28,8 @@ jobs:
 
         - name: Lint with ruff
           run: |
-            pixi run --environment lint ruff
+            pixi run ruff
 
         - name: Check formatting with black
           run: |
-            pixi run --environment lint black
+            pixi run black

README.md

@@ -41,13 +41,13 @@ pixi run <task name>
 So for example, to run all the tests run
 
 ```
-pixi run --environment test test
+pixi run test
 ```
 
 or to lint
 
 ```
-pixi run --environment lint lint
+pixi run lint
 ```
 
 If you would like to have interactive shell access (like a classic virtual environment) run