Validate migration files (#18203)

JSON Schema validation for data used by Gitea during migrations

Discussion at https://forum.forgefriends.org/t/common-json-schema-for-repository-information/563

Co-authored-by: Loïc Dachary <loic@dachary.org>

modules/migration/milestone.go

@@ -9,11 +9,11 @@ import "time"
 
 // Milestone defines a standard milestone
 type Milestone struct {
-	Title       string
-	Description string
-	Deadline    *time.Time
-	Created     time.Time
-	Updated     *time.Time
-	Closed      *time.Time
-	State       string // open, closed
+	Title       string     `json:"title"`
+	Description string     `json:"description"`
+	Deadline    *time.Time `json:"deadline"`
+	Created     time.Time  `json:"created"`
+	Updated     *time.Time `json:"updated"`
+	Closed      *time.Time `json:"closed"`
+	State       string     `json:"state"` // open, closed
 }