Fix logger string interpolation

[mwu3535]

Code is raising a panic due to the logger string not being correctly interpolated.

Error I got:

panic: interface conversion: interface {} is int, not string

goroutine 31 [running]:
github.com/newrelic/newrelic-client-go/v2/pkg/logging.createFieldMap(...)
	/Users/mwu/go/pkg/mod/github.com/newrelic/newrelic-client-go/v2@v2.26.0/pkg/logging/logrus_logger.go:101
github.com/newrelic/newrelic-client-go/v2/pkg/logging.LogrusLogger.Trace({0x140002aee78?}, {0x104fe35d2, 0xc}, {0x1400039a7a0?, 0x1400026de01?, 0x1400026de40?})
	/Users/mwu/go/pkg/mod/github.com/newrelic/newrelic-client-go/v2@v2.26.0/pkg/logging/logrus_logger.go:92 +0x1d4
github.com/newrelic/newrelic-client-go/v2/pkg/logs.(*Logs).batchWorker(0x1400091b440, {0x1053d1d38, 0x14000926120}, 0x0)
	/Users/mwu/go/pkg/mod/github.com/newrelic/newrelic-client-go/v2@v2.26.0/pkg/logs/logs_batch.go:161 +0x2e8
github.com/newrelic/newrelic-client-go/v2/pkg/logs.(*Logs).BatchMode.func2(0x8?)
	/Users/mwu/go/pkg/mod/github.com/newrelic/newrelic-client-go/v2@v2.26.0/pkg/logs/logs_batch.go:45 +0x74
created by github.com/newrelic/newrelic-client-go/v2/pkg/logs.(*Logs).BatchMode
	/Users/mwu/go/pkg/mod/github.com/newrelic/newrelic-client-go/v2@v2.26.0/pkg/logs/logs_batch.go:43 +0x220

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 38.90%. Comparing base (acdbc6d) to head (f24a3eb).

Files	Patch %	Lines
pkg/events/events_batch.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1104   +/-   ##
=======================================
  Coverage   38.90%   38.90%           
=======================================
  Files          86       86           
  Lines        5590     5590           
=======================================
  Hits         2175     2175           
  Misses       3249     3249           
  Partials      166      166           

Flag	Coverage Δ
unit	38.90% <0.00%> (ø)

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