chore: clean stale test/node_modules from Hardhat removal

The test/ directories in issuance and contracts were previously pnpm
workspace packages with their own package.json. After removing the
Hardhat test infrastructure, the orphaned test/node_modules remains
locally (pnpm does not clean up node_modules for removed workspace
packages). Add them to the clean scripts so `pnpm clean` removes
them for anyone who still has them.

Author: RembrandtK

packages/contracts/package.json

@@ -19,7 +19,7 @@
   "types": "index.d.ts",
   "scripts": {
     "prepack": "pnpm build",
-    "clean": "rm -rf artifacts/ cache/ types/ abis/ build/ dist/ coverage/",
+    "clean": "rm -rf artifacts/ cache/ types/ abis/ build/ dist/ coverage/ test/node_modules/",
     "build": "pnpm build:self",
     "build:self": "pnpm compile",
     "compile": "hardhat compile --quiet",

packages/issuance/package.json

@@ -24,7 +24,7 @@
     "build": "pnpm build:dep && pnpm build:self",
     "build:dep": "pnpm --filter '@graphprotocol/issuance^...' run build:self",
     "build:self": "pnpm compile && pnpm typechain",
-    "clean": "rm -rf artifacts/ forge-artifacts/ cache_forge/ coverage/ cache/ types/ typechain-src/ .eslintcache",
+    "clean": "rm -rf artifacts/ forge-artifacts/ cache_forge/ coverage/ cache/ types/ typechain-src/ .eslintcache test/node_modules/",
     "compile": "hardhat compile --quiet",
     "typechain": "typechain --target ethers-v6 --out-dir typechain-src 'artifacts/contracts/**/!(*.dbg).json' && tsc -p tsconfig.typechain.json && rm -rf typechain-src && echo '{\"type\":\"commonjs\"}' > types/package.json",
     "test": "forge test",