updatebot: Schedule updatebot for Firefly-III

Firefly-III only has a single Pod/container to manage with `updatebot`.

updatebot/projects/firefly-iii.toml

@@ -0,0 +1,13 @@
+[repo]
+url = "https://git.pyrocufflink.net/infra/kubernetes"
+token_file = "/run/secrets/updatebot/gitea.token"
+
+[projects.firefly-iii]
+kind = "kustomize"
+image = "docker.io/fireflyiii/core"
+tag_format = "version-{version}"
+
+[projects.firefly-iii.source]
+kind = "github"
+organization = "firefly-iii"
+repo = "firefly-iii"