mark jobs on nightlies to not fail ci

Author: tanmaykm

.github/workflows/ci.yml

@@ -27,10 +27,12 @@ jobs:
             arch: x64
             version: nightly
             experimental: true
+            continue-on-error: true
           - os: ubuntu-latest
             arch: x86
             version: nightly
             experimental: true
+            continue-on-error: true
           # test macOS and Windows with latest Julia only
           - os: macOS-latest
             arch: x64