Bump Hardhat Toolbox to v6 (#1002)

This is a follow up to #1000, where we finally bump the hardhat toolbox
verion to v6. Notable the _only_ change that that entails is going from
`hardhat-gas-reporter` `~1` to `~2`, which enables the gas reporting by
default.

After some more digging, I found that simply disbling the gas reporting
would cause tests to no longer fail (with it enabled, it would fail with
errors: "calling done() twice on test" and "cannot index property to on
undefined"). I narrowed the issue down to a specific test, which is now
disabled when gas reporting is on. Furthermore, I disabled gas reporting
by default, as I find it quite noisy. To run tests with a gas report:

```sh
HARDHAT_ENABLE_GAS_REPORTER=1 npm test
```

---------

Co-authored-by: Mikhail <16622558+mmv08@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>

Author: 3 people

hardhat.config.ts

@@ -30,8 +30,9 @@ const {
     PK,
     SOLIDITY_VERSION,
     SOLIDITY_SETTINGS,
-    HARDHAT_ENABLE_ZKSYNC = "0",
     HARDHAT_CHAIN_ID = 31337,
+    HARDHAT_ENABLE_ZKSYNC,
+    HARDHAT_ENABLE_GAS_REPORTER,
 } = process.env;
 
 const DEFAULT_MNEMONIC = "candy maple cake sugar pudding cream honey rich smooth crumble sweet treat";
@@ -170,6 +171,9 @@ const userConfig: HardhatUserConfig = {
     etherscan: {
         apiKey: ETHERSCAN_API_KEY,
     },
+    gasReporter: {
+        enabled: HARDHAT_ENABLE_GAS_REPORTER === "1",
+    },
 };
 if (NODE_URL) {
     userConfig.networks!.custom = {

test/libraries/SafeToL2Migration.spec.ts

@@ -334,13 +334,13 @@ describe("SafeToL2Migration library", () => {
             const guardBeforeMigration = await hre.ethers.provider.getStorage(safeAddress, GUARD_STORAGE_SLOT);
             const fallbackHandlerBeforeMigration = await hre.ethers.provider.getStorage(safeAddress, FALLBACK_HANDLER_STORAGE_SLOT);
 
-            await expect(
-                executeContractCallWithSigners(safe130, migration, "migrateToL2", [await singleton130l2.getAddress()], [user1], true),
-            );
+            await executeContractCallWithSigners(safe130, migration, "migrateToL2", [await singleton130l2.getAddress()], [user1], true);
 
             expect(await hre.ethers.provider.getStorage(safeAddress, 3)).to.be.eq(ownerCountBeforeMigration);
             expect(await hre.ethers.provider.getStorage(safeAddress, 4)).to.be.eq(thresholdBeforeMigration);
-            expect(await hre.ethers.provider.getStorage(safeAddress, 5)).to.be.eq(nonceBeforeMigration);
+            expect(await hre.ethers.provider.getStorage(safeAddress, 5)).to.be.eq(
+                hre.ethers.toBeHex(BigInt(nonceBeforeMigration) + 1n, 32),
+            );
             expect(await hre.ethers.provider.getStorage(safeAddress, GUARD_STORAGE_SLOT)).to.be.eq(guardBeforeMigration);
             expect(await hre.ethers.provider.getStorage(safeAddress, FALLBACK_HANDLER_STORAGE_SLOT)).to.be.eq(
                 fallbackHandlerBeforeMigration,

test/libraries/SafeToL2Setup.spec.ts

@@ -130,11 +130,11 @@ describe("SafeToL2Setup", () => {
                 ).to.be.rejectedWith("Safe must have not executed any tx");
             });
 
-            it("changes the expected storage slot without touching the most important ones", async () => {
+            it("changes the expected storage slot without touching the most important ones", async function () {
                 if (hre.network.zksync) {
                     // zksync doesn't support hardhat style traces
                     // and their traces only include calls without the storage changes
-                    return;
+                    this.skip();
                 }
 
                 const {