Avoid panic when values are numbers

When decrypting to dotenv we try to escape new line in the values
without taking into account the possibility that the value could be
something different than a string (e.g. an int).

This used to cause a panic when using `decrypt --output-format dotenv`.

Signed-off-by: billy4479 <giachi.ellero@gmail.com>

stores/dotenv/store.go

@@ -141,7 +141,13 @@ func (store *Store) EmitPlainFile(in sops.TreeBranches) ([]byte, error) {
 		if comment, ok := item.Key.(sops.Comment); ok {
 			line = fmt.Sprintf("#%s\n", comment.Value)
 		} else {
-			value := strings.Replace(item.Value.(string), "\n", "\\n", -1)
+			value, ok := item.Value.(string)
+			if !ok {
+				value = stores.ValToString(item.Value)
+			} else {
+				value = strings.ReplaceAll(value, "\n", "\\n")
+			}
+
 			line = fmt.Sprintf("%s=%s\n", item.Key, value)
 		}
 		buffer.WriteString(line)