Downgrade gin to v1.9.1 for Go 1.22 compatibility

backend/go.mod

@@ -3,7 +3,7 @@ module sale
 go 1.22
 
 require (
-	github.com/gin-gonic/gin v1.12.0
+	github.com/gin-gonic/gin v1.9.1
 	github.com/glebarez/sqlite v1.11.0
 	github.com/golang-jwt/jwt/v5 v5.3.1
 	github.com/joho/godotenv v1.5.1
@@ -21,7 +21,7 @@ require (
 	github.com/cloudwego/base64x v0.1.6 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.12 // indirect
-	github.com/gin-contrib/sse v1.1.0 // indirect
+	github.com/gin-contrib/sse v0.1.0 // indirect
 	github.com/glebarez/go-sqlite v1.21.2 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
@@ -43,12 +43,9 @@ require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
-	github.com/quic-go/qpack v0.6.0 // indirect
-	github.com/quic-go/quic-go v0.59.0 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.3.1 // indirect
-	go.mongodb.org/mongo-driver/v2 v2.5.0 // indirect
 	golang.org/x/arch v0.22.0 // indirect
 	golang.org/x/net v0.52.0 // indirect
 	golang.org/x/sync v0.20.0 // indirect