Explicitly specify shellcheck directives to ignore a (non-available) source file

Author: kostis

.github/workflows/shellcheck.yml

@@ -7,5 +7,3 @@ jobs:
       - uses: actions/checkout@v4
       - name: Run ShellCheck
         uses: ludeeus/action-shellcheck@master
-        env:
-          SHELLCHECK_OPTS: -x

scripts/setup_venv.sh

@@ -1,14 +1,16 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # This script sets up the python environment if it doesn't exist yet.
 # It should be sourced (i.e. called with "source scripts/setup_venv.sh")
 # so that the python environment will be available in the calling shell.
 
 if [ -d "venv" ]; then
+    # shellcheck source=/dev/null
     source venv/bin/activate
 else
     # Create a venv and activate it
     python3 -m venv venv
+    # shellcheck source=/dev/null
     source venv/bin/activate
     # Install dependencies from PyPi
     pip3 install -r requirements.txt