Switch from zip to 7z for PDBs archive on AppVeyor

This reduces its size by more than 1.5 times.

appveyor.yml

@@ -83,7 +83,7 @@ for:
 
   artifacts:
   - path: '*.msi'
-  - path: '*-pdb.zip'
+  - path: '*-pdb.7z'
 
   deploy:
   - provider: Webhook

release/windows/build-transmission.ps1

@@ -64,7 +64,7 @@ function global:Build-Transmission([string] $PrefixDir, [string] $Arch, [string]
     New-Item -Path $ArtifactsDir -ItemType Directory -ErrorAction Ignore | Out-Null
     $MsiPackage = (Get-ChildItem (Join-Path $BuildDir dist msi 'transmission-*.msi'))[0]
     Move-Item -Path $MsiPackage.FullName -Destination $ArtifactsDir
-    Invoke-NativeCommand cmake -E chdir $DebugSymbolsDir 7z a -y (Join-Path $ArtifactsDir "$($MsiPackage.BaseName)-pdb.zip")
+    Invoke-NativeCommand cmake -E chdir $DebugSymbolsDir 7z a -y (Join-Path $ArtifactsDir "$($MsiPackage.BaseName)-pdb.7z")
 }
 
 function global:Test-Transmission([string] $DepsPrefixDir, [string] $SourceDir) {