fix(ci): error in building electron due to extensions

.github/actions/build-electron/action.yml

@@ -6,7 +6,7 @@ inputs:
     description: "The architecture to build for: x64, arm64"
     required: true
   extension:
-    description: "Platform specific extension to build: dmg, deb, exe"
+    description: "Platform specific extensions to copy in the output: dmg, deb, rpm, exe"
     required: true
 runs:
   using: composite
@@ -32,7 +32,7 @@ runs:
       shell: bash
       run: |
         mkdir -p upload;
-        for ext in ${{ join(inputs.extension, ' ') }};
+        for ext in ${{ inputs.extension }};
         do
           file=$(find out/make -name "*.$ext" -print -quit);
           cp "$file" "upload/TriliumNextNotes-${{ github.ref_name }}-${{ inputs.os }}-${{ inputs.arch }}.$ext";