Merge pull request pytroll#17 from pkhalaj/ci/import-error-httpx

Install  as a testing dependency in `ci.yml`

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        python -m pip install ruff pytest pytest-lazy-fixtures pytest-asyncio pytest-cov
+        python -m pip install httpx ruff pytest pytest-lazy-fixtures pytest-asyncio pytest-cov
         python -m pip install -e .
     - name: Test with pytest
       run: |