build: reduce dependabot update frequency

[Fdawgs]

See https://github.com/pinojs/pino/pull/1356

[coveralls]

Pull Request Test Coverage Report for Build 1927115915

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 1926958611:	0.0%
Covered Lines:	350
Relevant Lines:	350

---

💛 - Coveralls

[Fdawgs]

@mcollina would you mind merging this when you get a second please?

Also have the following hanging about:

https://github.com/pinojs/pino-http/pull/202 https://github.com/pinojs/pino-elasticsearch/pull/134 https://github.com/pinojs/express-pino-logger/pull/98 https://github.com/pinojs/pino-socket/pull/57

[Fdawgs]

Thank you!