Use % for percentage in string format

[EdwardBetts]

Change Summary

Related issue number

Checklist

• Unit tests for the changes exist
• Tests pass on CI and coverage remains at 100%
• Documentation reflects the changes where applicable
• changes/<pull request or issue id>-<github username>.md file added describing change
  (see changes/README.md for details)

[codecov]

Codecov Report

Merging #1960 (7053878) into master (bf9cc4a) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            master     #1960    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           21        21            
  Lines         3909      4133   +224     
  Branches       788       832    +44     
==========================================
+ Hits          3909      4133   +224     

Impacted Files	Coverage Δ
pydantic/color.py	100.00% <100.00%> (ø)
pydantic/json.py	100.00% <0.00%> (ø)
pydantic/tools.py	100.00% <0.00%> (ø)
pydantic/types.py	100.00% <0.00%> (ø)
pydantic/utils.py	100.00% <0.00%> (ø)
pydantic/errors.py	100.00% <0.00%> (ø)
pydantic/fields.py	100.00% <0.00%> (ø)
pydantic/schema.py	100.00% <0.00%> (ø)
pydantic/typing.py	100.00% <0.00%> (ø)
pydantic/generics.py	100.00% <0.00%> (ø)
... and 7 more

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[samuelcolvin]

Looks good to me.

Please add a change description and make sure tests are coving this case.

[samuelcolvin]

bump

[samuelcolvin]

@EdwardBetts any chance you could finish this?