Use POSIX-compliant string comparison in bash tests

This replaces '==' with '=' in bash test expressions for POSIX
compliance. While '==' works in bash, '=' is the POSIX standard and
ensures better portability across different shells.

Author: jserv

.ci/test-netdev.sh

@@ -23,7 +23,7 @@ TEST_NETDEV() {
     local NETDEV="$1"
     local CMD_PREFIX=""
 
-    if [ "$NETDEV" == "tap" ]; then
+    if [ "$NETDEV" = "tap" ]; then
         CMD_PREFIX="sudo "
     fi