ci: fix prebuilt.yml (#7956)

.github/workflows/prebuilt.yml

@@ -17,6 +17,7 @@ jobs:
         tag=${GITHUB_REF##*/}
         wget https://github.com/vlang/v/releases/download/$tag/v_linux.zip
         unzip v_linux.zip
+        cd v
         ./v -version
     - name: Test V
       run: |
@@ -36,6 +37,7 @@ jobs:
         tag=${GITHUB_REF##*/}
         wget https://github.com/vlang/v/releases/download/$tag/v_macos.zip
         unzip v_macos.zip
+        cd v
         ./v -version
     - name: Test V
       run: |
@@ -50,6 +52,7 @@ jobs:
         Set-Variable -Name "tag" -Value $env:GITHUB_REF.split("/", 3)[-1]
         & curl -L https://github.com/vlang/v/releases/download/$tag/v_windows.zip -o v_windows.zip
         & unzip .\v_windows.zip
+        & cd v
         & .\v.exe -version
     - name: Test V
       run: |