Remove redundant platform dependency definition

There were two electroniccats:mbed platform dependency definitions listed in the
arduino/actions/libraries/compile-examples action's platforms input. The one that specifies the package index URL is the
complete one and the other is unnecessary.

Author: per1234

.github/workflows/compile-examples.yml

@@ -52,10 +52,9 @@ jobs:
         with:
           fqbn: ${{ matrix.board.fqbn }}
           platforms: |
+            # Use Board Manager to install the latest release of Arduino mbed Boards to get the toolchain
             - source-url: "https://electroniccats.github.io/Arduino_Boards_Index/package_electroniccats_index.json"
               name: "electroniccats:mbed"
-            # Use Board Manager to install the latest release of Arduino mbed Boards to get the toolchain
-            - name: "electroniccats:mbed"
             # Overwrite the Board Manager installation with the local platform
             - source-path: "./"
               name: "electroniccats:mbed"