*: switch order of "clean" command

Previously, it would delete the node_modules directory before calling
lerna, which would not exist because it just got removed.

With this change, lerna acts before being removed from the root
node_modules directory.

package.json

@@ -17,7 +17,7 @@
     "test": "lerna --concurrency 1 run test --stream --ignore @graphprotocol/indexer-service",
     "test:ci": "lerna --concurrency 1 run test:ci --stream --ignore @graphprotocol/indexer-service",
     "update-common-ts": "./scripts/update-common-ts.sh 1.8.3",
-    "clean": "rm -rf ./node_modules && lerna run clean",
+    "clean": "lerna run clean && rm -rf ./node_modules",
     "compile": "lerna run compile"
   },
   "devDependencies": {