ci: specify architectures for Linux targets

Specify architectures for each Linux package target (AppImage,
Snap, deb, rpm) so releases are built for x64, armv7l, and arm64.
Previously the targets were listed as simple strings which did not
declare per-target archs; making them objects with an "arch" array
ensures multi-arch artifacts are produced during CI and packaging.

Author: 4gray

package.json

@@ -41,10 +41,38 @@
         "linux": {
             "category": "Video",
             "target": [
-                "AppImage",
-                "Snap",
-                "deb",
-                "rpm"
+                {
+                    "target": "AppImage",
+                    "arch": [
+                        "x64",
+                        "armv7l",
+                        "arm64"
+                    ]
+                },
+                {
+                    "target": "Snap",
+                    "arch": [
+                        "x64",
+                        "armv7l",
+                        "arm64"
+                    ]
+                },
+                {
+                    "target": "deb",
+                    "arch": [
+                        "x64",
+                        "armv7l",
+                        "arm64"
+                    ]
+                },
+                {
+                    "target": "rpm",
+                    "arch": [
+                        "x64",
+                        "armv7l",
+                        "arm64"
+                    ]
+                }
             ],
             "artifactName": "${name}-${version}-${os}-${arch}.${ext}"
         },