CI: Install NSIS in the windows-patches action

The windows-2022 runner had NSIS pre-installed. The windows-2025 runners
are slimmer and do not have NSIS installed. The windows-2025 runners do
have winget available, which can be used to install NSIS.

The windows-2025 runners do not have NSIS in PATH by default, so we need
to specify it manually in the config files.

Follow-up to ac19ea6633.

.github/actions/windows-patches/action.yaml

@@ -68,6 +68,12 @@ runs:
         Expand-Archive -Path $windows_zip -DestinationPath bin
         Expand-Archive -Path $nsis_zip -DestinationPath nsis
 
+    - name: Install NSIS
+      shell: pwsh
+      run: |
+        # Install NSIS
+        winget install --silent --accept-package-agreements --accept-source-agreements --disable-interactivity -e --id NSIS.NSIS
+
     - name: Install rclone and pandoc
       shell: pwsh
       run: |

.github/actions/windows-patches/config.toml

@@ -4,7 +4,7 @@ log_level = "trace"
 [env]
 # On CI these should be in %PATH%
 sevenzip_path = "7z"
-makensis_path = "makensis"
+makensis_path = "C:/Program Files (x86)/NSIS/makensis.exe"
 pandoc_path = "pandoc"
 pdbcopy_path = "C:/Program Files (x86)/Windows Kits/10/Debuggers/x64/pdbcopy.exe"