pin older cargo wix version

Author: Stephan Dilly

.github/workflows/ci.yml

@@ -86,7 +86,7 @@ jobs:
     - name: Build MSI (windows)
       if: matrix.os == 'windows-latest'
       run: |
-        cargo install cargo-wix
+        cargo install cargo-wix --version 0.3.1
         cargo wix --no-build --nocapture --output ./target/wix/gitui.msi
         ls -l ./target/wix/gitui.msi