Update checkout version and fix deprecated envvars

Author: philwhineray

.github/workflows/publish.yml

@@ -8,8 +8,8 @@ jobs:
       - name: Extract tag/branch variables
         shell: bash
         run: >
-           echo "##[set-output name=tag;]$(echo ${GITHUB_REF#refs/tags/}|grep -v '/')";
-           echo "##[set-output name=branch;]$(echo ${GITHUB_REF#refs/heads/}|grep -v '/')";
+           echo "tag=$(echo ${GITHUB_REF#refs/tags/}|grep -v '/')" >> $GITHUB_OUTPUT
+           echo "branch=$(echo ${GITHUB_REF#refs/heads/}|grep -v '/')" >> $GITHUB_OUTPUT
         id: extract
       - name: Write secret keys
         run: >
@@ -19,9 +19,9 @@ jobs:
            then
              eval "$(ssh-agent)";
              ssh-add firehol_org_publish_key;
-             echo "##[set-output name=has_ssh_key;]true";
-             echo "##[set-output name=ssh_agent_pid;]$SSH_AGENT_PID";
-             echo "##[set-output name=ssh_auth_sock;]$SSH_AUTH_SOCK";
+             echo "has_ssh_key=true" >> $GITHUB_OUTPUT
+             echo "ssh_agent_pid=$SSH_AGENT_PID" >> $GITHUB_OUTPUT
+             echo "ssh_auth_sock=$SSH_AUTH_SOCK" >> $GITHUB_OUTPUT
            fi;
            rm -f firehol_org_publish_key
         env:
@@ -40,7 +40,7 @@ jobs:
            echo "Not publishing '${{steps.extract.outputs.branch}}'";
            echo "##[set-output name=skip;]true"
         id: check
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: ./.github/workflows/setup.sh
       - run: make
       - name: Deploy website ${{steps.extract.outputs.branch}}