libgit2sharp.yml: try fetch v2 fetch-depth: 0

Author: lytico

.github/workflows/libgit2sharp.yml

@@ -12,9 +12,9 @@ jobs:
     runs-on: ubuntu-20.04
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
       with:
-          fetch-depth: 3
+          fetch-depth: 0
     - name: Setup .NET
       uses: actions/setup-dotnet@v1
       with: