feat: fix CI: use go install for goveralls instead of go get

[Copilot]

fix: #12

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[coveralls]

Pull Request Test Coverage Report for Build 21559242538

Details

• 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 75.532%

---

Totals
Change from base Build 6289916862:	0.0%
Covered Lines:	71
Relevant Lines:	94

---

💛 - Coveralls