bump tox>=4.5.1, fix setenv in tox.ini

setenv defined explicitly until regression fixed in tox:
* tox-dev/tox#2972
* tox-dev/tox#2872

Author: mr-mixas

.github/workflows/tests.yml

@@ -40,8 +40,7 @@ jobs:
 
     - name: Install dependencies
       run: |
-        pip install --quiet --upgrade pip setuptools
-        pip install --quiet --upgrade tox==3.27.0
+        pip install --quiet --upgrade pip setuptools tox>=4.5.1
 
     - name: Run test without coverage
       if: ${{ matrix.tox-env != 'coverage' }}

tox.ini

@@ -24,7 +24,7 @@ deps =
     coverage
 
 setenv =
-    {[testenv:essential]setenv}
+    PYTHONHASHSEED = 1
 
 [testenv:linters]
 commands =
@@ -47,7 +47,7 @@ deps =
     {[testenv:essential]deps}
 
 setenv =
-    {[testenv:essential]setenv}
+    PYTHONHASHSEED = 1
 
 [darglint]
 docstring_style=google