Update nightly-linux64.yml

allow scheduled nightly to be manually run as well

Author: ofTheo

.github/workflows/nightly-linux64.yml

@@ -24,7 +24,12 @@ name: nightly-linux64
 on:
  schedule:
    - cron: "0 6 * * *"
-
+ workflow_dispatch:
+    inputs:
+          release:
+            description: 'release'     
+            required: true
+            default: 'nightly'
 env:
   ccache: ccache