Use new pip resolver

Author: anders-kiaer

.github/workflows/webviz-config.yml

@@ -50,14 +50,12 @@ jobs:
 
       - name: 📦 Install webviz-config with dependencies
         run: |
-          pip install 'pandas==${{ matrix.pandas-version }}'
           pip install --upgrade pip
-          pip install .
+          pip install --use-feature=2020-resolver . 'pandas==${{ matrix.pandas-version }}'
 
       - name: 📦 Install test dependencies
         run: |
-          pip install .[tests]
-          pip install dash[testing]
+          pip install --use-feature=2020-resolver .[tests]
           wget https://chromedriver.storage.googleapis.com/$(wget https://chromedriver.storage.googleapis.com/LATEST_RELEASE -q -O -)/chromedriver_linux64.zip
           unzip chromedriver_linux64.zip
   

CONTRIBUTING.md

@@ -515,11 +515,7 @@ To run tests it is necessary to first install the [selenium chrome driver](https
 Then install the Python development requirements:
 ```bash
 pip install .[tests]
-pip install dash[testing]
 ```
-The second of these commands appears to be necessary as long as
-[this `pip` issue is open](https://github.com/pypa/pip/issues/4957).
-
 You can then run the tests using
 ```bash
 pytest tests --forked

setup.py

@@ -25,6 +25,7 @@ def get_long_description() -> str:
 TESTS_REQUIRES = [
     "bandit",
     "black",
+    "dash[testing]",
     "jsonschema",
     "mock",
     "mypy",