Align our subprocess usage with current best practices. (#12940)

* Align our subprocess usage with current best practices.

* remove unused import

* Apply suggestions from code review

Co-authored-by: Ryan <fauxpark@gmail.com>

* fix the cpp invocation for older python

* allow for unprompted installation

* make sure qmk new-keyboard works on windows

Co-authored-by: Ryan <fauxpark@gmail.com>

util/install/void.sh

@@ -3,7 +3,7 @@
 _qmk_install() {
     echo "Installing dependencies"
 
-    sudo xbps-install \
+    sudo xbps-install $SKIP_PROMPT \
         gcc git make wget unzip zip \
         python3-pip \
         avr-binutils avr-gcc avr-libc \