remove some mimalloc, netsurf and iconv references

.github/actions/install/action.yml

@@ -58,29 +58,3 @@ runs:
       run: |
         mkdir -p v8
         ln -s ${{ inputs.cache-dir }}/v8/libc_v8.a v8/libc_v8.a
-
-    - name: Cache libiconv
-      id: cache-libiconv
-      uses: actions/cache@v4
-      env:
-        cache-name: cache-libiconv
-      with:
-        path: ${{ inputs.cache-dir }}/libiconv
-        key: vendor/libiconv/libiconv-1.17
-
-    - name: download libiconv
-      if: ${{ steps.cache-libiconv.outputs.cache-hit != 'true' }}
-      shell: bash
-      run: make download-libiconv
-
-    - name: build libiconv
-      shell: bash
-      run: make build-libiconv
-
-    - name: build mimalloc
-      shell: bash
-      run: make install-mimalloc
-
-    - name: build netsurf
-      shell: bash
-      run: make install-netsurf