ci: bump go to latest 1.20.x for vulncheck (#2520)

* bump go to 1.20.4 for vulncheck

* use latest version of go

* run at 3am UTC

* Updated go version

* Revert "Updated go version"

This reverts commit effe7b7.

---------

Co-authored-by: Yaru Wang <yaru@informal.systems>
Co-authored-by: Milan Mulji <98309852+mmulji-ic@users.noreply.github.com>
Co-authored-by: yaruwangway <69694322+yaruwangway@users.noreply.github.com>

.github/workflows/nightly-tests.yml

@@ -4,16 +4,7 @@ on:
   workflow_dispatch:
   schedule:
     # run every day at 03:00 UTC
-    #        ┌───────────── minute (0 - 59)
-    #        │  ┌───────────── hour (0 - 23)
-    #        │  │ ┌───────────── day of the month (1 - 31)
-    #        │  │ │ ┌───────────── month (1 - 12 or JAN-DEC)
-    #        │  │ │ │ ┌───────────── day of the week (0 - 6 or SUN-SAT)
-    #        │  │ │ │ │
-    #        │  │ │ │ │
-    #        │  │ │ │ │
-    #        *  * * * *  
-    - cron: "0 0 * * *"
+    - cron: "0 3 * * *"
 
 jobs:
 
@@ -30,7 +21,8 @@ jobs:
       - uses: actions/checkout@v3.5.2
       - uses: actions/setup-go@v4
         with:
-          go-version: 1.20.3
+          go-version: "1.20"
+          check-latest: true
       - name: run-vulncheck
         id: vulncheck
         run: make vulncheck