update clean recipe

justfile

@@ -1,2 +1,14 @@
 clean:
-    rm -r dist/ __pycache__/
+    #!/bin/sh
+    if [ ! -d "dist" ] && [ ! -d "__pycache__" ]; then
+        echo "Nothing to clean."
+        exit 0
+    fi
+    if [ -d "dist" ]; then
+        echo "Removing dist/"
+        rm -r dist/
+    fi
+    if [ -d "__pycache__" ]; then
+        echo "Removing __pycache__/"
+        rm -r "__pycache__"
+    fi