fix: 双击ddim文件使用软件包安装器打开

双击ddim文件使用软件包安装器打开

Bug: https://pms.uniontech.com/bug-view-285473.html
Log: 双击ddim文件使用软件包安装器打开

assets/deepin-deb-installer.desktop

@@ -5,7 +5,7 @@ Comment=Package Installer helps users install and remove local packages, and sup
 Exec=deepin-deb-installer %F
 GenericName=Package Installer
 Icon=deepin-deb-installer
-MimeType=application/vnd.debian.binary-package;application/x-deb;
+MimeType=application/vnd.debian.binary-package;application/x-deb;application/x-ddim;
 Name=Package Installer
 StartupNotify=false
 Terminal=false