basic-install.sh: Use `grep -E` instead of `egrep`

Signed-off-by: a1346054 <36859588+a1346054@users.noreply.github.com>

automated install/basic-install.sh

@@ -358,7 +358,7 @@ package_manager_detect() {
         # These variable names match the ones for apt-get. See above for an explanation of what they are for.
         PKG_INSTALL=("${PKG_MANAGER}" install -y)
         # CentOS package manager returns 100 when there are packages to update so we need to || true to prevent the script from exiting.
-        PKG_COUNT="${PKG_MANAGER} check-update | egrep '(.i686|.x86|.noarch|.arm|.src)' | wc -l || true"
+        PKG_COUNT="${PKG_MANAGER} check-update | grep -E '(.i686|.x86|.noarch|.arm|.src)' | wc -l || true"
         OS_CHECK_DEPS=(grep bind-utils)
         INSTALLER_DEPS=(git dialog iproute newt procps-ng which chkconfig ca-certificates)
         PIHOLE_DEPS=(cronie curl findutils sudo unzip libidn2 psmisc libcap nmap-ncat jq)