Fetch tags

We need this for auto-publish.

Upstream issue: actions/checkout#338

Author: matklad

.github/workflows/ci.yaml

@@ -23,6 +23,8 @@ jobs:
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
 
     - name: Install Rust toolchain
       uses: actions-rs/toolchain@v1