feat: add `github-inactivity` helm chart

[kseniyashaydurova]

Add new github-inactivity helm chart: https://saritasa.atlassian.net/browse/SD-448 (search inactive repos in organization github and notify required people in slack and email)

Implemented this app on cloud EKS, added deployment with helm chart for simplicity: https://deploy.saritasa.cloud/applications/github-inactivity?view=tree&resource=

Other related PRs:

• https://github.com/saritasa-nest/saritasa-devops-github-activity/pull/2
• https://github.com/saritasa-nest/saritasa-terraform-modules/pull/46
• https://github.com/saritasa-nest/saritasa-cloud-kubernetes-aws/pull/26

[kseniyashaydurova]

@dmitry-mightydevops suggested to move github-inactivity chart directly to repo, soclosing this PR, new changes should be checked here - https://github.com/saritasa-nest/saritasa-devops-github-inactivity/pulls