enable shellcheck

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I3b383bc2649100e996cc9ed715b110855ab405f3
diff --git a/gen/regenerate-meson b/gen/regenerate-meson
index 6c32c46..56bc2c6 100755
--- a/gen/regenerate-meson
+++ b/gen/regenerate-meson
@@ -19,5 +19,5 @@
 
 $SDBUSPP_GEN_MESON \
     --command meson \
-    --directory $REPO_ROOT \
-    --output $REPO_ROOT/gen
+    --directory "$REPO_ROOT" \
+    --output "$REPO_ROOT/gen"