Add govulncheck to the CI

[rogercoll]

We should check for vulnerabilities in each push: https://pkg.go.dev/golang.org/x/vuln/cmd/govulnchec

For example, the current Server (Go 1.20) has the following vulnerabilities:

Vulnerability #2: GO-2024-2887
    Unexpected behavior from Is methods for IPv4-mapped IPv6 addresses in
    net/netip
  More info: https://pkg.go.dev/vuln/GO-2024-2887
  Standard library
    Found in: net/netip@go1.21.10
    Fixed in: net/netip@go1.21.11
    Example traces found:
Error:       #1:  server.server.Start, which eventually calls netip.Addr.IsLoopback
Error:       #2:  server.server.Start, which eventually calls netip.Addr.IsMulticast