fix: modernize windows installer with Inno Setup (#867)

.github/workflows/build.yml

@@ -55,13 +55,36 @@ jobs:
             dist/*.tar.gz
             dist/*.zip
 
-      - name: Generate Installers
-        run: |
-          mkdir -p dist-installers
-          ./scripts/generate-installers.sh ./dist-installers
+  installer:
+    name: Windows installers
+    needs: [ build ]
+    runs-on: windows-2022
 
-      - name: Upload Installers
-        uses: actions/upload-artifact@v4
-        with:
-          name: backrest-snapshot-installers
-          path: dist-installers/*.exe
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Download build artifacts
+      uses: actions/download-artifact@v4
+      with:
+        name: backrest-snapshot-builds
+
+    - name: Unzip artifacts and compile Inno Setup installers
+      shell: powershell
+      run: |
+        mkdir windows_installers
+        foreach ($arch in "x86_64", "arm64") {
+          $src = "backrest_Windows_$arch"
+          Expand-Archive ".\${src}.zip"
+          cp build\windows\* $src
+          & "c:\Program Files (x86)\Inno Setup 6\ISCC.exe" /DArch=$arch ${src}\installer.iss
+          cp "$src\Output\*" windows_installers
+        }
+
+    - name: Upload installers
+      uses: actions/upload-artifact@v4
+      with:
+        name: backrest-snapshot-installers
+        path: windows_installers\*.exe