bootstrap: Do not build paru on tmpfs

The tmp fs can sometimes be very small, too small in fact to build
paru on.

bootstrap/install_packages.sh

@@ -45,10 +45,12 @@ install_paru() {
     fi
 
     # use tmp dir to make paru
-    target=$(mktemp -d)
+    tempdir=".paru"
-    git clone https://aur.archlinux.org/paru.git "$target"
+    git clone https://aur.archlinux.org/paru.git "$tempdir"
-    cd "$target" || exit
+    pushd "$tempdir" || exit 1
     makepkg -si
+    popd || exit 1
+    rm -rf "$tempdir"
 }
 
 update_repos() {