Add version file for prometheus bridge

[eddyariki]

Adds version.go for bridges/prometheus.

Part of #8272

Up for discussions

Should I include changes to bridges/prometheus/producer.go and bridges/prometheus/producer_test.go in this PR? Or should it be separated?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.3%. Comparing base (0e6a3d2) to head (2d2d0a5).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #8401   +/-   ##
=====================================
  Coverage   82.3%   82.3%           
=====================================
  Files        179     179           
  Lines      13728   13728           
=====================================
  Hits       11307   11307           
  Misses      2023    2023           
  Partials     398     398           

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[flc1125]

It would be even better if a version number were added here.

opentelemetry-go-contrib/bridges/prometheus/producer.go

Lines 71 to 73 in cff6a19

	Scope: instrumentation.Scope{
	Name: scopeName,
	},