tests: Suppress cargo-component output

Suppress the output from cargo-component when we first run it to check
if it's available, otherwise you may see the following

  $ pytest test/test_wasm-wasi-component.py
  which: no go in (/home/andrew/.local/bin:/home/andrew/bin:/usr/share/Modules/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin)
  error: no such command: `component`

  	View all installed commands with `cargo --list`
  	Find a package to install `component` with `cargo search cargo-component

Note: This didn't stop the tests from working, just an aesthetic issue.

Closes: #1410
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

Author: ac000

test/unit/applications/lang/wasm_component.py

@@ -11,7 +11,10 @@ class ApplicationWasmComponent(ApplicationProto):
     @staticmethod
     def prepare_env(script):
         try:
-            subprocess.check_output(['cargo', 'component', '--help'])
+            subprocess.check_output(
+                ['cargo', 'component', '--help'],
+                stderr=subprocess.STDOUT,
+            )
         except (subprocess.CalledProcessError, FileNotFoundError):
             return None