tox: remove cat coverage index from tox, it's not very useful anyway

tox.ini

@@ -116,7 +116,6 @@ commands =
 
 
 [testenv:mypy-core]
-allowlist_externals = cat
 commands =
     {envpython} -m pip install --use-pep517 -e .[testing,optional]
     {envpython} -m pip install orgparse # used it core.orgmode?
@@ -127,13 +126,11 @@ commands =
         --txt-report  .coverage.mypy-core \
         --html-report .coverage.mypy-core \
         {posargs}
-    cat .coverage.mypy-core/index.txt
 
 
 # specific modules that are known to be mypy compliant (to avoid false negatives)
 # todo maybe split into separate jobs? need to add comment how to run
 [testenv:mypy-misc]
-allowlist_externals = cat
 commands =
     {envpython} -m pip install --use-pep517 -e .[testing,optional]
 
@@ -172,8 +169,6 @@ commands =
         --txt-report  .coverage.mypy-misc \
         --html-report .coverage.mypy-misc \
         {posargs}
-    # txt report is a bit more convenient to view on CI
-    cat .coverage.mypy-misc/index.txt
 
     {envpython} -m mypy --install-types --non-interactive \
         tests