Run go staticcheck & removing reported warnings

[Avinash041]

Running go staticcheck & removed reported warnings.
Used below staticcheck.conf file as the staticcheck configuration file:

checks = ["all", "-ST1005", "-ST1000", "-ST1003", "-ST1016", "-ST1020", "-ST1021", "-ST1022", "-ST1023"]
initialisms = ["ACL", "API", "ASCII", "CPU", "CSS", "DNS", "EOF", "GUID", "HTML", "HTTP", "HTTPS", "ID", "IP", "JSON", "QPS", "RAM", "RPC", "SLA", "SMTP", "SQL", "SSH", "TCP", "TLS", "TTL", "UDP", "UI", "GID", "UID", "UUID", "URI", "URL", "UTF8", "VM", "XML", "XMPP", "XSRF", "XSS", "SIP", "RTP", "AMQP", "DB", "TS"]
dot_import_whitelist = ["github.com/mmcloughlin/avo/build", "github.com/mmcloughlin/avo/operand", "github.com/mmcloughlin/avo/reg", "github.com/free5gc/openapi/models"]
http_status_code_whitelist = ["200", "400", "404", "500"]

Below are warnings reported by staticcheck:

cmd/main.go:41:2: rand.Seed has been deprecated since Go 1.20 and an alternative has been available since Go 1.0: As of Go 1.20 there is no reason to call Seed with a random value. Programs that call Seed with a known value to get a specific sequence of results should use New(NewSource(seed)) to obtain a local random generator. (SA1019)
pkg/factory/factory.go:4:2: "io/ioutil" has been deprecated since Go 1.19: As of Go 1.16, the same functionality is now provided by package [io] or package [os], and those implementations should be preferred in new code. See the specific function documentation for details. (SA1019)