Try some powershell

.ci/deploy.bat

@@ -1,13 +0,0 @@
-@ECHO OFF
-SETLOCAL ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
-cd ..
-set BUCKET=qb64-dev-builds
-set TIMEX=%TIME: =0%
-set archive=qb64_%DATE:~10,4%-%DATE:~4,2%-%DATE:~7,2%-%TIMEX:~0,2%-%TIMEX:~3,2%-%TIMEX:~6,2%_%GITHUB_SHA:~0,7%_win-%PLATFORM%.7z
-7z a -xr@qb64\.ci\common-exclusion.list -xr@qb64\.ci\win-exclusion.list %archive% qb64
-
-aws --output text --query Contents[].Key s3api list-objects --bucket %BUCKET% --prefix win-%PLATFORM% > olddevbuilds.txt
-
-aws s3 cp %archive% s3://%BUCKET%/win-%PLATFORM%/
-
-for /F "tokens=*" %%G in (olddevbuilds.txt) do aws s3 rm s3://%BUCKET%/%%G

.ci/deploy.ps1

@@ -0,0 +1,11 @@
+$Bucket = "qb64-dev-builds"
+$Timestamp = (Get-Date).ToUniversalTime().ToString("yyyy-MM-dd-HH-mm-ss")
+$Filename = "qb64_${Timestamp}_$($Env:GITHUB_SHA.substring(0,7))_win-${Env:PLATFORM}.7z"
+
+Set-Location ..
+7z a -xr@qb64\.ci\common-exclusion.list -xr@qb64\.ci\win-exclusion.list $Filename qb64
+$OldFiles = aws --output json --query Contents[].Key s3api list-objects --bucket $Bucket --prefix win-$Env:PLATFORM | ConvertFrom-Json
+aws s3 cp $Filename "s3://${Bucket}/win-${Env:PLATFORM}/"
+foreach ($f in $OldFiles) {
+    aws s3 rm "s3://$Bucket/$f"
+}

.github/workflows/run.yml

@@ -76,7 +76,7 @@ jobs:
         aws-region: us-east-2
     - name: Publish to S3
       if: github.event_name == 'push'
-      run: .ci/deploy.bat
+      run: .ci/deploy.ps1
 
   windows-x64-build:
     runs-on: windows-latest