Fix logging without format string

[schlenk]

• Any changes relevant to users are recorded in the CHANGELOG.md.
• The documentation has been updated, if necessary.
• New code is annotated.
• Changes are covered by tests.

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When trying to hook opentelemetry up to the code, it blows up trying to consume log messages without a format string.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 63.80%. Comparing base (37024ad) to head (10364b5).

Files	Patch %	Lines
src/oic/oic/provider.py	50.00%	3 Missing ⚠️
src/oic/oauth2/base.py	0.00%	1 Missing ⚠️
src/oic/utils/authn/saml.py	0.00%	1 Missing ⚠️
src/oic/utils/http_util.py	0.00%	1 Missing ⚠️
src/oic/utils/keyio.py	0.00%	1 Missing ⚠️
src/oic/utils/rp/__init__.py	0.00%	1 Missing ⚠️
src/oic/utils/rp/oauth2.py	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@           Coverage Diff           @@
##           master     #871   +/-   ##
=======================================
  Coverage   63.80%   63.80%           
=======================================
  Files          64       64           
  Lines       11879    11879           
  Branches     2155     2155           
=======================================
  Hits         7579     7579           
  Misses       3697     3697           
  Partials      603      603           

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