Use consistent bash5 style for conditionals and quoting

install/config/git.sh

@@ -1,8 +1,8 @@
 # Set identification from install inputs
-if [[ -n "${OMARCHY_USER_NAME//[[:space:]]/}" ]]; then
+if [[ -n ${OMARCHY_USER_NAME//[[:space:]]/} ]]; then
   git config --global user.name "$OMARCHY_USER_NAME"
 fi
 
-if [[ -n "${OMARCHY_USER_EMAIL//[[:space:]]/}" ]]; then
+if [[ -n ${OMARCHY_USER_EMAIL//[[:space:]]/} ]]; then
   git config --global user.email "$OMARCHY_USER_EMAIL"
 fi