create install-dep-gd action, drop GD from main-PDL build

Author: mohawk2

github-actions/install-dep-gd/action.yml

@@ -0,0 +1,20 @@
+name: Install GD
+runs:
+  using: "composite"
+  steps:
+    - name: Install GD (via apt-get)
+      shell: bash
+      run: |
+          if ${{ toJSON( runner.os == 'Linux' ) }}; then
+            echo "::group::Install GD (via apt-get)"
+            sudo apt-get -y update && sudo apt-get install --no-install-recommends -y libgd-dev
+            echo "::endgroup::"
+          fi
+    - name: Install GD (via brew)
+      shell: bash
+      run: |
+          if ${{ toJSON( runner.os == 'macOS' ) }}; then
+            echo "::group::Install GD (via brew)"
+            brew install gd
+            echo "::endgroup::"
+          fi

github-actions/install-dep-pdl-dep/action.yml

@@ -8,7 +8,7 @@ runs:
         if ${{ toJSON( runner.os == 'Linux' ) }}; then
           echo "::group::Install main PDL deps (via apt-get)"
           sudo apt-get -y update && \
-            sudo apt-get install --no-install-recommends -y build-essential libgd-dev libproj-dev proj-bin libcfitsio-dev libreadline-dev libvpx-dev libgsl0-dev netpbm libnetpbm10-dev
+            sudo apt-get install --no-install-recommends -y build-essential libproj-dev proj-bin libcfitsio-dev libreadline-dev libvpx-dev libgsl0-dev netpbm libnetpbm10-dev
           echo "::endgroup::"
         elif ${{ toJSON( runner.os == 'macOS' ) }}; then
           echo "::group::Install main PDL deps (via brew)"