create install-dep-gsl action, remove GSL from general PDL config

docker/Dockerfile

@@ -20,7 +20,7 @@ RUN apt-get update \
 	&& apt-get update \
 	&& apt-get install --no-install-recommends -y \
 		build-essential gfortran \
-		libcfitsio-dev libreadline-dev libvpx-dev libgsl0-dev \
+		libcfitsio-dev libreadline-dev libvpx-dev \
 		netpbm libnetpbm10-dev
 
 FROM deps as builder

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

@@ -0,0 +1,20 @@
+name: Install GSL
+runs:
+  using: "composite"
+  steps:
+    - name: Install GSL (via apt-get)
+      shell: bash
+      run: |
+          if ${{ toJSON( runner.os == 'Linux' ) }}; then
+            echo "::group::Install GSL (via apt-get)"
+            sudo apt-get -y update && sudo apt-get install --no-install-recommends -y libgsl0-dev
+            echo "::endgroup::"
+          fi
+    - name: Install GSL (via brew)
+      shell: bash
+      run: |
+          if ${{ toJSON( runner.os == 'macOS' ) }}; then
+            echo "::group::Install GSL (via brew)"
+            brew install gsl
+            echo "::endgroup::"
+          fi

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

@@ -8,12 +8,12 @@ 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 libcfitsio-dev libreadline-dev libvpx-dev libgsl0-dev netpbm libnetpbm10-dev
+            sudo apt-get install --no-install-recommends -y build-essential libcfitsio-dev libreadline-dev libvpx-dev netpbm libnetpbm10-dev
           echo "::endgroup::"
         elif ${{ toJSON( runner.os == 'macOS' ) }}; then
           echo "::group::Install main PDL deps (via brew)"
           brew update
-          HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK=1 brew install netpbm gsl
+          HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK=1 brew install netpbm
           echo "::endgroup::"
         fi
     - name: Install extra optional main PDL deps

regression-vagrant/install-pdl

@@ -6,7 +6,7 @@ function start() {
 	sudo apt-get update
 	sudo apt-get install -y build-essential libx11-dev pgplot5 libplplot-dev libvpx-dev libxpm-dev libcfitsio3-dev libreadline-dev
 	if [ "$DISABLE_FORTRAN" != 1 ]; then sudo apt-get install -y gfortran; fi # set DISABLE_FOTRAN = 1 to not install gfortran
-	sudo apt-get install -y libxi-dev libxmu-dev freeglut3-dev libgsl0-dev libnetpbm10-dev # for OpenGL
+	sudo apt-get install -y libxi-dev libxmu-dev freeglut3-dev libnetpbm10-dev # for OpenGL
 	sudo apt-get install -y xvfb # for OpenGL
 	export PGPLOT_DEV=/NULL
 	cpanm --installdeps PDL || ( cat ~/.cpanm/build.log && false )