Downgrade yaml to support ordered map parsing

go.mod

@@ -4,5 +4,5 @@ go 1.20
 
 require (
 	github.com/iancoleman/strcase v0.3.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
 )

go.sum

@@ -1,5 +1,7 @@
 github.com/iancoleman/strcase v0.3.0 h1:nTXanmYxhfFAMjZL34Ov6gkzEsSJZ5DbhxWjvSASxEI=
 github.com/iancoleman/strcase v0.3.0/go.mod h1:iwCmte+B7n89clKwxIoIXy/HfoL7AsD47ZCWhYzw7ho=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/parser/parse.go

@@ -2,7 +2,7 @@ package parser
 
 import (
 	"errors"
-	"gopkg.in/yaml.v3"
+	"gopkg.in/yaml.v2"
 	"nanoc/internal/datatype"
 	"nanoc/internal/symbol"
 	"os"
@@ -15,15 +15,17 @@ func ParseSchema(path string) (datatype.PartialSchema, error) {
 		return nil, err
 	}
 
-	m := map[string]interface{}{}
+	m := yaml.MapSlice{}
 	err = yaml.Unmarshal(b, m)
 	if err != nil {
 		return nil, err
 	}
 
 	var schema datatype.PartialSchema
 
-	for k, v := range m {
+	for _, e := range m {
+		k := e.Key.(string)
+		v := e.Value
 		if strings.HasPrefix(k, symbol.Enum+" ") {
 			s, err := parseEnumSchema(k, v)
 			if err != nil {