Drop 3.7 from tox

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py37, py38, py39, py310, lint, typing
+envlist = py38, py39, py310, lint, typing
 skip_missing_interpreters = true
 skipsdist = true
 # pyproject.toml: To use a PEP 517 build-backend you are required to configure tox to use an isolated_build
@@ -9,34 +9,34 @@ isolated_build = True
 basepython = python3
 
 [testenv]
-allowlist_externals = 
+allowlist_externals =
     flake8
     scripts/zhinst_qcodes_symlink.py
 deps =
-   py{37,38,39,310}: -rrequirements.txt
+   py{38,39,310}: -rrequirements.txt
    pytest-cov
-commands = 
+commands =
     # install toolkit first to ensure the correct version
-    {envpython} -m pip install git+https://github.com/zhinst/zhinst-toolkit 
+    {envpython} -m pip install git+https://github.com/zhinst/zhinst-toolkit
     {envpython} -m pip install .
     {envpython} scripts/zhinst_qcodes_symlink.py
     {envpython} -m pytest --cov=zhinst.qcodes
 
 [testenv:lint]
-deps = 
+deps =
     flake8
     flake8-docstrings
-commands = 
+commands =
     flake8
 
 [testenv:black]
-deps = 
+deps =
     black==22.3.0
-commands = 
+commands =
     black . --check --diff
 
 [testenv:typing]
-deps = 
+deps =
     mypy
-commands = 
+commands =
     mypy src