CLOUD-3175: prevent parse error on macos version check (#93)

@cobbr2 noticed this error while he was testing the recent m2/m3 mac
changes:
```
ln: /usr/local/bin/docker: File exists
ln: /usr/local/bin/docker-compose: File exists

Parse error: bad token
    <stdin>:1

Rancher Desktop has been installed successfully
```

This is caused by an undefined variable, so this PR fixes that.

Rick also suggested I rewrite the version checking logic to avoid using
`bc -l` to make it simpler.

VERSION

@@ -1 +1 @@
-0.1.53
+0.1.54

formula/ih-core.rb

@@ -1,5 +1,5 @@
 class IhCore < Formula
-  VERSION="0.1.53"
+  VERSION="0.1.54"
   desc "Brew formula for installing core tools used at Included Health engineering."
   homepage "https://github.com/ConsultingMD/homebrew-ih-public"
   license "CC BY-NC-ND 4.0"

lib/core/rancher/step.sh

@@ -12,6 +12,8 @@ RANCHER_AUGMENT_DST="$IH_DEFAULT_DIR/11_rancher.sh"
 PLIST_SRC="$IH_CORE_LIB_DIR/core/rancher/io.rancherdesktop.profile.defaults.plist"
 PLIST_DST="$HOME/Library/Preferences/io.rancherdesktop.profile.defaults.plist"
 
+REQUIRED_APPLE_SILICON_MACOS_VERSION="13.3"
+
 # Check if the step has been installed and return 0 if it has.
 # Otherwise return 1.
 function ih::setup::core.rancher::test() {
@@ -51,10 +53,8 @@ function ih::setup::core.rancher::test() {
 
   # Use vz (requires macOS >=13.3) instead of qemu on M3 macs to resolve issues.
   # More details: https://github.com/lima-vm/lima/issues/1996
-  local macos_version=$(ih::arch::get_macos_version)
   if ih::arch::is_m2_or_m3_mac; then
-    if (( $(echo "$macos_version < 13.3" | bc -l) )); then
-      ih::log::error "macOS version 13.3 or higher is required for M3 Macs."
+    if ! ih::arch::check_macos_version_compatibility "$REQUIRED_APPLE_SILICON_MACOS_VERSION"; then
       return 1
     elif ! grep -q "<string>vz</string>" "$PLIST_DST"; then
       ih::log::debug "The PLIST file needs to be updated to use 'vz' for M3 Macs."
@@ -163,8 +163,7 @@ function ih::setup::core.rancher::install() {
     # Use vz (requires macOS >=13.3) instead of qemu on M3 macs to resolve issues.
     # More details: https://github.com/lima-vm/lima/issues/1996
     if ih::arch::is_m2_or_m3_mac; then
-      if (( $(echo "$macos_version < 13.3" | bc -l) )); then
-        ih::log::error "macOS version 13.3 or higher is required for M3 Macs."
+      if ! ih::arch::check_macos_version_compatibility "$REQUIRED_APPLE_SILICON_MACOS_VERSION"; then
         return 1 # Abort the installation for M3 Macs
       elif ! grep -q "<string>vz</string>" "$PLIST_DST"; then
         ih::log::debug "Updating PLIST to use 'vz' for Virtualization for M3 Macs."

lib/utils/arch.sh

@@ -26,6 +26,28 @@ ih::arch::get_macos_version() {
   sw_vers -productVersion | awk -F '.' '{ printf("%d.%d\n", $1, $2) }'
 }
 
+ih::arch::check_macos_version_compatibility() {
+  local required_version="$1"
+  local current_version=$(ih::arch::get_macos_version)
+
+  # Splitting the current and required versions into major and minor components
+  IFS='.' read -r current_major current_minor _ <<< "$current_version"
+  IFS='.' read -r required_major required_minor _ <<< "$required_version"
+
+  # Ensure variables are integers (default to 0 if empty for robust comparison)
+  current_major=${current_major:-0}
+  current_minor=${current_minor:-0}
+  required_major=${required_major:-0}
+  required_minor=${required_minor:-0}
+
+  if (( current_major > required_major )) || { (( current_major == required_major )) && (( current_minor >= required_minor )); }; then
+    return 0 # meets minimum requirement
+  else
+    ih::log::error "macOS version $required_version or higher is required. Current version: $current_version."
+    return 1
+  fi
+}
+
 ih::arch::is_m2_or_m3_mac() {
   local hw_model=$(sysctl -n machdep.cpu.brand_string)
   [[ "$hw_model" == *"M2"* ]] || [[ "$hw_model" == *"M3"* ]]