ci: fix windows build version (#785)

Author: monkeyWie

.github/workflows/build.yml

@@ -51,7 +51,7 @@ jobs:
           Invoke-WebRequest -Uri "https://github.com/jrsoftware/issrc/raw/main/Files/Languages/Unofficial/ChineseSimplified.isl" -OutFile "ChineseSimplified.isl"
           mv ChineseSimplified.isl "C:\Program Files (x86)\Inno Setup 6\Languages\"
 
-          go build -tags nosqlite -ldflags="-w -s -X github.com/GopeedLab/gopeed/pkg/base.Version=$VERSION" -buildmode=c-shared -o ui/flutter/windows/libgopeed.dll github.com/GopeedLab/gopeed/bind/desktop
+          go build -tags nosqlite -ldflags="-w -s -X github.com/GopeedLab/gopeed/pkg/base.Version=$env:VERSION" -buildmode=c-shared -o ui/flutter/windows/libgopeed.dll github.com/GopeedLab/gopeed/bind/desktop
           cd ui/flutter
           $TAG = "v$env:VERSION"
           flutter build windows