Logs: Severity Text string does not match the spec

[tigrannajaryan]

Describe your environment
Mac OS X
Python 3.9.6

Steps to reproduce
Run Getting Started, metrics example.

What is the expected behavior?
Severity Text = WARN as defined in the spec.

What is the actual behavior?
Severity Text = WARNING

{
    "body": "Anonymous player is rolling the dice: 5",
    "severity_number": "<SeverityNumber.WARN: 13>",
    "severity_text": "WARNING",
    "attributes": {
        "otelSpanID": "7d0581e1f3f51bea",
        "otelTraceID": "8b346ee9af8718bf73a4318d073cbbb1",
        "otelTraceSampled": true,
        "otelServiceName": "dice-server"
    },
    "dropped_attributes": 0,
    "timestamp": "2023-11-22T17:01:36.027744Z",
    "trace_id": "0x8b346ee9af8718bf73a4318d073cbbb1",
    "span_id": "0x7d0581e1f3f51bea",
    "trace_flags": 1,
    "resource": "BoundedAttributes({'telemetry.sdk.language': 'python', 'telemetry.sdk.name': 'opentelemetry', 'telemetry.sdk.version': '1.21.0', 'service.name': 'dice-server', 'telemetry.auto.version': '0.42b0'}, maxlen=None)"
}

Additional context
Part of review open-telemetry/community#1751