feat: add github_user_external_identity_by_saml data source#3268

Phil-Browne wants to merge 1 commit intointegrations:mainintegrations/terraform-provider-github:mainfrom

Phil-Browne:feat/data-source-external-identity-by-samlPhil-Browne/terraform-provider-github:feat/data-source-external-identity-by-samlCopy head branch name to clipboard