feat: accept level in capitals

[balaji-atoa]

💬BASED ON:

#2022 (comment)

🚀UPDATES:

• converted level to lower case if passed in capitals.

✅ Added UnitTests.

[balaji-atoa]

HELP NEEDED! @jsumners

• Tried reproducing the same in my local by using the exact environment versions for node and npm. but, this passed.
  

• ran npm run test-ci & it passed in my local.

$ npm run test-ci

> pino@9.3.2 test-ci
> npm run lint && npm run transpile && tap --ts --no-check-coverage --coverage-report=lcovonly && npm run test-types


> pino@9.3.2 lint
> eslint .


> pino@9.3.2 transpile
> node ./test/fixtures/ts/transpile.cjs

​ SKIP ​ test/broken-pipe.test.js
 ~ skipping on windows

​ SKIP ​ TAP
 ~ test/browser-early-console-freeze.test.js

​ SKIP ​ test/http.test.js
 ~ http request support via serializer without request connection

​ SKIP ​ test/transport/module-link.test.js
 ~ pino.transport with package

​ SKIP ​ test/transport/module-link.test.js                                                                                                                     
 ~ pino.transport with package as a target                                                                                                                      

​ SKIP ​ test/transport/module-link.test.js
 ~ pino({ transport })

​ SKIP ​ test/transport/module-link.test.js
 ~ pino({ transport }) from a wrapped dependency

​ SKIP ​ test/broken-pipe.test.js 1 skip of 1 3.142ms
 ~ skipping on windows

​ SKIP ​ test/browser-early-console-freeze.test.js 2s
​ SKIP ​ test/http.test.js 1 skip of 16 155.235ms
 ~ http request support via serializer without request connection

​ SKIP ​ test/transport/module-link.test.js 4 skip of 4 19.466ms
 ~ pino.transport with package
 ~ pino.transport with package as a target
 ~ pino({ transport })
 ~ pino({ transport }) from a wrapped dependency

Suites:   ​44 passed​, ​1 skip​, ​45 of 45 completed​
Asserts:  ​​​1334 passed​, ​7 skip​, ​of 1341​

> pino@9.3.2 test-types
> tsc && tsd && ts-node test/types/pino.ts

[16:39:30.633] CUSTOMDEBUG (9012): test3
[16:39:30.640] INFO (9012): test4
[16:39:30.641] CUSTOMERROR (9012): test5
[16:39:30.642] CUSTOMNETWORK (9012): test6
[16:39:30.622] INFO (9012): test2
    some: "bindings"
[16:39:30.625] INFO (9012): test2
[16:39:30.626] INFO (9012): test2

[mcollina]

lgtm