[pkg/stanza] Logger uses wrong case for severity

[jsirianni]

While running the contrib collector against a local build of log-collection, I noticed that the log-collection logger uses info while the logging exporter is using INFO.

2022-03-12T23:10:48.456Z	info	regex/regex.go:109	cache hit: opentelemetry-node-agent-collector-v4qwj_default_otc-container-0dc9ede9c077d55438dda1d907cb5e491df5639524542e161fa48814c10f7d6d.log	{"kind": "receiver", "name": "filelog", "operator_id": "regex_parser", "operator_type": "regex_parser"}
2022-03-12T23:10:48.616Z	INFO	loggingexporter/logging_exporter.go:69	LogsExporter	{"#logs": 43}

Not a big deal, but it does look funny when both are logging next too each other.