change the format of the diagnostic counts to avoid pluralizing because "informations" looks weird

[DetachHead]

fixes #58

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

rclip (https://github.com/yurijmikhalevich/rclip)
- 30 errors, 14 warnings, 0 informations 
+ 30 errors, 14 warnings, 0 notes 

pyinstrument (https://github.com/joerick/pyinstrument)
- 41 errors, 5 warnings, 0 informations 
+ 41 errors, 5 warnings, 0 notes 

pyp (https://github.com/hauntsaninja/pyp)
- 6 errors, 0 warnings, 0 informations 
+ 6 errors, 0 warnings, 0 notes 

Expression (https://github.com/cognitedata/Expression)
- 297 errors, 0 warnings, 0 informations 
+ 297 errors, 0 warnings, 0 notes 

dd-trace-py (https://github.com/DataDog/dd-trace-py)
- 10227 errors, 460 warnings, 0 informations 
+ 10227 errors, 460 warnings, 0 notes 

mkosi (https://github.com/systemd/mkosi)
- 9 errors, 0 warnings, 0 informations 
+ 9 errors, 0 warnings, 0 notes 

antidote (https://github.com/Finistere/antidote)
- 728 errors, 34 warnings, 0 informations 
+ 728 errors, 34 warnings, 0 notes 

mypy-protobuf (https://github.com/dropbox/mypy-protobuf)
- 21 errors, 24 warnings, 0 informations 
+ 21 errors, 24 warnings, 0 notes 

pandera (https://github.com/pandera-dev/pandera)
- 1314 errors, 10 warnings, 0 informations 
+ 1314 errors, 10 warnings, 0 notes 

PyWinCtl (https://github.com/Kalmat/PyWinCtl)
- 8 errors, 23 warnings, 0 informations 
+ 8 errors, 23 warnings, 0 notes 

xarray-dataclasses (https://github.com/astropenguin/xarray-dataclasses)
- 57 errors, 145 warnings, 0 informations 
+ 57 errors, 145 warnings, 0 notes 

pydantic (https://github.com/samuelcolvin/pydantic)
- 67 errors, 0 warnings, 0 informations 
+ 67 errors, 0 warnings, 0 notes 

spack (https://github.com/spack/spack)
- 23775 errors, 78 warnings, 0 informations 
+ 23775 errors, 78 warnings, 0 notes 

pandas (https://github.com/pandas-dev/pandas)
- 1934 errors, 3 warnings, 0 informations 
+ 1934 errors, 3 warnings, 0 notes 

bidict (https://github.com/jab/bidict)
- 37 errors, 2 warnings, 0 informations 
+ 37 errors, 2 warnings, 0 notes 

alectryon (https://github.com/cpitclaudel/alectryon)
- 22 errors, 37 warnings, 0 informations 
+ 22 errors, 37 warnings, 0 notes 

koda-validate (https://github.com/keithasaurus/koda-validate)
- 175 errors, 3 warnings, 0 informations 
+ 175 errors, 3 warnings, 0 notes 

speedrun.com_global_scoreboard_webapp (https://github.com/Avasam/speedrun.com_global_scoreboard_webapp)
- 31 errors, 8 warnings, 1 information 
+ 31 errors, 8 warnings, 1 note 

trio (https://github.com/python-trio/trio)
- 3974 errors, 10 warnings, 0 informations 
+ 3974 errors, 10 warnings, 0 notes 

steam.py (https://github.com/Gobot1234/steam.py)
- 8389 errors, 26 warnings, 0 informations 
+ 8389 errors, 26 warnings, 0 notes 

Tanjun (https://github.com/FasterSpeeding/Tanjun)
- 2398 errors, 6751 warnings, 0 informations 
+ 2398 errors, 6751 warnings, 0 notes 

hydra-zen (https://github.com/mit-ll-responsible-ai/hydra-zen)
- 148 errors, 0 warnings, 183 informations 
+ 148 errors, 0 warnings, 183 notes 

operator (https://github.com/canonical/operator)
- 29 errors, 0 warnings, 0 informations 
+ 29 errors, 0 warnings, 0 notes 

AutoSplit (https://github.com/Toufool/AutoSplit)
- 516 errors, 29 warnings, 7 informations 
+ 516 errors, 29 warnings, 7 notes 

discord.py (https://github.com/Rapptz/discord.py)
- 61 errors, 14 warnings, 0 informations 
+ 61 errors, 14 warnings, 0 notes 

freqtrade (https://github.com/freqtrade/freqtrade)
- 596 errors, 38 warnings, 0 informations 
+ 596 errors, 38 warnings, 0 notes 

pandas-stubs (https://github.com/pandas-dev/pandas-stubs)
- 1557 errors, 0 warnings, 0 informations 
+ 1557 errors, 0 warnings, 0 notes 

materialize (https://github.com/MaterializeInc/materialize)
- 10 errors, 304 warnings, 0 informations 
+ 10 errors, 304 warnings, 0 notes