refactor: use robfigcron for validation after lagoon replacements (#368)

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/google/go-cmp v0.6.0
 	github.com/hashicorp/go-retryablehttp v0.7.7
 	github.com/k8up-io/k8up/v2 v2.11.1
+	github.com/robfig/cron/v3 v3.0.1
 	github.com/spf13/cobra v1.8.1
 	github.com/uselagoon/machinery v0.0.29
 	github.com/vshn/k8up v1.99.99

go.sum

@@ -706,6 +706,7 @@ github.com/qri-io/starlib v0.4.2-0.20200213133954-ff2e8cd5ef8d/go.mod h1:7DPO4do
 github.com/quasilyte/go-consistent v0.0.0-20190521200055-c6f3937de18c/go.mod h1:5STLWrekHfjyYwxBRVRXNOSewLJ3PWfDJd1VyTS21fI=
 github.com/remyoudompheng/bigfft v0.0.0-20170806203942-52369c62f446/go.mod h1:uYEyJGbgTkfkS4+E/PavXkNJcbFIpEtjt2B0KDQ5+9M=
 github.com/rhnvrm/simples3 v0.6.1/go.mod h1:Y+3vYm2V7Y4VijFoJHHTrja6OgPrJ2cBti8dPGkC3sA=
+github.com/robfig/cron/v3 v3.0.1 h1:WdRxkvbJztn8LMz/QEvLN5sBU+xKpSqwwUO1Pjr4qDs=
 github.com/robfig/cron/v3 v3.0.1/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzGIFLtro=
 github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af/go.mod h1:XWv6SoW27p1b0cqNHllgS5HIMJraePCO15w5zCzIWYg=
 github.com/rogpeppe/go-internal v1.1.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=