opentelemetry-opentracing-shim: add fixed setuptools version for testing

Use latest version < 78.0.0 because they removed support to parse the
setup.cfg (description-file) used in opentracing.

Author: xrmx

tox.ini

@@ -128,6 +128,8 @@ deps =
 
   opentelemetry-exporter-otlp-proto-http: -r {toxinidir}/exporter/opentelemetry-exporter-otlp-proto-http/test-requirements.txt
 
+  # setuptools 78 removed support for syntax used in opentracing package
+  opentracing-shim: setuptools==77.0.3
   opentracing-shim: -r {toxinidir}/shim/opentelemetry-opentracing-shim/test-requirements.txt
 
   opencensus-shim: -r {toxinidir}/shim/opentelemetry-opencensus-shim/test-requirements.txt