ci: build test fails randomly

Build test fails randomly when ran on GitHub actions:

[@graphprotocol/contracts]: An unexpected error occurred:
[@graphprotocol/contracts]: 
[@graphprotocol/contracts]: Error: spawn /home/runner/.cache/hardhat-nodejs/compilers-v2/linux-amd64/solc-linux-amd64-v0.7.6+commit.7338295f EACCES
[@graphprotocol/contracts]:     at Process.ChildProcess._handle.onexit (node:internal/child_process:284:19)
[@graphprotocol/contracts]:     at onErrorNT (node:internal/child_process:477:16)
[@graphprotocol/contracts]:     at processTicksAndRejections (node:internal/process/task_queues:82:21) {
[@graphprotocol/contracts]:   errno: -13,
[@graphprotocol/contracts]:   code: 'EACCES',
[@graphprotocol/contracts]:   syscall: 'spawn /home/runner/.cache/hardhat-nodejs/compilers-v2/linux-amd64/solc-linux-amd64-v0.7.6+commit.7338295f',
[@graphprotocol/contracts]:   path: '/home/runner/.cache/hardhat-nodejs/compilers-v2/linux-amd64/solc-linux-amd64-v0.7.6+commit.7338295f',
[@graphprotocol/contracts]:   spawnargs: [ '--standard-json' ],
[@graphprotocol/contracts]:   cmd: '/home/runner/.cache/hardhat-nodejs/compilers-v2/linux-amd64/solc-linux-amd64-v0.7.6+commit.7338295f --standard-json'
[@graphprotocol/contracts]: }
[@graphprotocol/contracts]: Process exited (exit code 1), completed in 8s 876ms

[@graphprotocol/sdk]: Process started
[@graphprotocol/sdk]: 
[@graphprotocol/sdk]: > @graphprotocol/sdk@0.3.0 clean
[@graphprotocol/sdk]: > rm -rf build
[@graphprotocol/sdk]: 
Error: [@graphprotocol/sdk]: src/deployments/network/actions/bridge-to-l1.ts(10,56): error TS2306: File '/home/runner/work/contracts/contracts/packages/contracts/index.d.ts' is not a module.
Error: [@graphprotocol/sdk]: src/deployments/network/actions/bridge-to-l1.ts(141,54): error TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string | TransactionReceipt'.
[@graphprotocol/sdk]:   Type 'undefined' is not assignable to type 'string | TransactionReceipt'.
Error: [@graphprotocol/sdk]: src/deployments/network/deployment/contracts/load.ts(44,8): error TS2306: File '/home/runner/work/contracts/contracts/packages/contracts/index.d.ts' is not a module.
Error: [@graphprotocol/sdk]: src/helpers/epoch.ts(2,35): error TS2306: File '/home/runner/work/contracts/contracts/packages/contracts/index.d.ts' is not a module.
[@graphprotocol/sdk]: Process exited (exit code 1), completed in 2s 756ms
Done in 11s 639ms
Error: Process completed with exit code 1.

This is a known problem with hardhat:

• https://github.com/NomicFoundation/hardhat/issues/4490 (if this is the root cause, updating to latest hardhat could solve it)
• https://github.com/NomicFoundation/hardhat/issues/4491 (this is most likely the root cause)

Start with the failing GitHub Actions build and the Hardhat compiler cache path shown in the log, then compare the repository's Hardhat version with the linked upstream issues. Review the reported SDK errors in src/deployments/network/actions/bridge-to-l1.ts, src/deployments/network/deployment/contracts/load.ts, and src/helpers/epoch.ts. Done means the complete build passes reliably in CI.