test: Update sayHello process to use cowpy

- Changed the environment specification from 'python=3.8' to 'cowpy'.
- Updated the script to utilize cowpy for output instead of a Python command.

This modification enhances the testing of Pixi environments by leveraging cowpy for greeting functionality.

Signed-off-by: Edmund Miller <[email protected]>

Author: edmundmiller

tests/checks/pixi-env.nf

@@ -9,13 +9,13 @@ workflow {
  */
 
 process sayHello {
-    pixi 'python=3.8'
+    pixi 'cowpy'
 
     output:
     stdout
 
     script:
-    '''
-    python -c "import sys; print(f'Hello from Python {sys.version_info.major}.{sys.version_info.minor}!')"
-    '''
+    """
+    cowpy "hello pixi"
+    """
 }