ci: pass GITHUB_TOKEN to tests

brownie sometimes fails on CI with the following message

    ConnectionError: Status 403 when retrieving repo brownie-mix/token information from GHAPI: 'API rate limit exceeded for 40.77.45.130. (But here's the good news: Authenticated requests get a higher rate limit. Check out the documentation for more details.)'

This passes GITHUB_TOKEN onto the test environment to increase the rate limit.

.github/workflows/ci.yml

@@ -69,6 +69,7 @@ jobs:
       env:
         TEST_TYPE: ${{ matrix.type }}
         GITHUB_ETHERSCAN: ${{ secrets.GITHUB_ETHERSCAN }}
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       shell: bash
       run: |
         bash "scripts/ci_test_${TEST_TYPE}.sh"