fix(compat): suppress command -v stderr in Bash 3.0

In Bash 3.0, `command -v` prints errors to stderr for missing commands
unlike modern bash which is silent. Redirect stderr to /dev/null.

Author: Chemaclass

src/check_os.sh

@@ -28,11 +28,11 @@ function bashunit::check_os::init() {
 }
 
 function bashunit::check_os::is_ubuntu() {
-  command -v apt >/dev/null
+  command -v apt >/dev/null 2>&1
 }
 
 function bashunit::check_os::is_alpine() {
-  command -v apk >/dev/null
+  command -v apk >/dev/null 2>&1
 }
 
 function bashunit::check_os::is_nixos() {