Fix misplaced defer in manifest caching

In #5797, I introduced the outer `do`-block here, but did not move the existing `defer` from the now inner `do`-block.

Related to rdar://101956252

Author: neonichu

Sources/PackageLoading/ManifestLoader.swift

@@ -385,6 +385,8 @@ public final class ManifestLoader: ManifestLoaderProtocol {
         // shells out and compiles the manifest, finally output a JSON
         observabilityScope.emit(debug: "evaluating manifest for '\(packageIdentity)' v. \(packageVersion?.description ?? "unknown")")
         do {
+            defer { closeAfterWrite.perform() }
+
             try self.evaluateManifest(
                 packageIdentity: key.packageIdentity,
                 manifestPath: key.manifestPath,
@@ -396,8 +398,6 @@ public final class ManifestLoader: ManifestLoaderProtocol {
                 dispatchPrecondition(condition: .onQueue(callbackQueue))
 
                 do {
-                    defer { closeAfterWrite.perform() }
-
                     let evaluationResult = try result.get()
                     // only cache successfully parsed manifests
                     let parseManifest = try self.parseManifest(