[windows] Upload .zip files

We need to serve not only `.tar.gz` files, but `.zip` files as well, as
many windows users do not have an easy way to extract tarballs.

pipelines/scheduled/coverage/coverage.yml.signature

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pipelines/scheduled/launch_signed_jobs.yml.signature

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pipelines/scheduled/launch_upload_jobs.yml.signature

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utilities/upload_julia.sh

@@ -79,6 +79,11 @@ elif [[ "${OS}" == "windows" || "${OS}" == "windowsnogpl" ]]; then
 
     # Add the `.exe` to our upload targets
     UPLOAD_EXTENSIONS+=( "exe" )
+
+    # Use powershell to create a `.zip` file to upload as well
+    echo "--- [windows] make zip"
+    powershell Compress-Archive "$(cygpath -w "$(pwd)/${JULIA_INSTALL_DIR}")" "${UPLOAD_FILENAME}.zip"
+    UPLOAD_EXTENSIONS+=( "zip" )
 fi
 
 echo "--- GPG-sign the tarball"