Fix modpack env field being required (#270)

src/database/models/version_item.rs

@@ -467,8 +467,8 @@ impl Version {
             ",
             id as VersionId,
         )
-            .execute(&mut *transaction)
-            .await?;
+        .execute(&mut *transaction)
+        .await?;
 
         // delete version
 

src/validate/pack.rs

@@ -27,7 +27,7 @@ pub struct PackFormat<'a> {
 pub struct PackFile<'a> {
     pub path: &'a str,
     pub hashes: std::collections::HashMap<FileHash, &'a str>,
-    pub env: std::collections::HashMap<EnvType, SideType>,
+    pub env: Option<std::collections::HashMap<EnvType, SideType>>,
     #[validate(custom(function = "validate_download_url"))]
     pub downloads: Vec<&'a str>,
 }