fix(ci): run tests serially to prevent issues due to modcache cleaning

Author: not-matthias

.github/workflows/ci.yml

@@ -39,7 +39,7 @@ jobs:
       - uses: moonrepo/setup-rust@v1
       - run: |
           cd go-runner
-          cargo nextest run --all
+          cargo nextest run --all -j 1
         env:
           CODSPEED_GO_PKG_VERSION: ${{ github.head_ref || github.ref_name }}