refactor: move things to packages (#39)

internal/updater/updater.go

@@ -0,0 +1,19 @@
+package updater
+
+type ReleaseInfo struct {
+	Version        string
+	ChangelogEntry string
+}
+
+type Updater func(string) (string, error)
+
+type NewUpdater func(ReleaseInfo) Updater
+
+func WithInfo(info ReleaseInfo, constructors ...NewUpdater) []Updater {
+	updaters := make([]Updater, 0, len(constructors))
+	for _, constructor := range constructors {
+		updaters = append(updaters, constructor(info))
+	}
+
+	return updaters
+}