feat: Update to SASS 1.65 (#14)

## Description
Updates to SASS 1.65 and resolves a conflict in function naming: the rem()
function, and mixin, have been renamed as 'toRem' to avoid using 'rem' as
that is now a reserved function.

## Issue
https://jira.dev.bbc.co.uk/browse/GEL-2103

Author: randombitsUK

.nvmrc

@@ -0,0 +1 @@
+v18.17.1

lib/tools/_rem.scss

@@ -26,7 +26,7 @@ $gel-tools-rem-enable--fallback: true !default;
 //
 // @author          Kaelig - https://github.com/guardian/guss-rem
 //
-@function rem($value, $baseline: $gel-base-font-size) {
+@function toRem($value, $baseline: $gel-base-font-size) {
 
     // if function is disabled then return the value
     @if ($gel-tools-rem-enable--function == false) {
@@ -61,7 +61,7 @@ $gel-tools-rem-enable--fallback: true !default;
 //
 // @author          Shaun Bent
 //
-@mixin rem($property, $value) {
+@mixin toRem($property, $value) {
 
     // Return the pixel value first
     @if ($gel-tools-rem-enable--mixin == false or $gel-tools-rem-enable--fallback == true) {
@@ -70,7 +70,7 @@ $gel-tools-rem-enable--fallback: true !default;
 
     // Pass the px value into the rem function
     @if ($gel-tools-rem-enable--function == true and $gel-tools-rem-enable--mixin == true) {
-        #{$property}: rem($value);
+        #{$property}: toRem($value);
     }
 
 }

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "gel-sass-tools",
-  "version": "2.1.0",
+  "version": "3.0.0",
   "description": "A collection of Sass Settings & Tools which align to key GEL values",
   "main": "_sass-tools.scss",
   "scripts": {
@@ -34,10 +34,10 @@
   },
   "homepage": "https://github.com/bbc/gel-sass-tools",
   "dependencies": {
-    "sass-mq": "5.0.1"
+    "sass-mq": "6.0.0"
   },
   "devDependencies": {
-    "sass": "1.42.1",
-    "sass-mq": "5.0.1"
+    "sass": "1.65.1",
+    "sass-mq": "6.0.0"
   }
 }

package.json

@@ -24,15 +24,15 @@
 
 // Lets test our rem functions
 .rem-function {
-    font-size: rem(16px);   // Expected: 1rem
-    font-size: rem(24px);   // Expected: 1.5rem
-    font-size: rem(32px);   // Expected: 2rem
+    font-size: toRem(16px);   // Expected: 1rem
+    font-size: toRem(24px);   // Expected: 1.5rem
+    font-size: toRem(32px);   // Expected: 2rem
 }
 
 .rem-mixin {
-    @include rem('font-size', 16px);    // Expected: 1rem
-    @include rem('font-size', 24px);    // Expected: 1.5rem
-    @include rem('font-size', 32px);    // Expected: 2rem
+    @include toRem('font-size', 16px);    // Expected: 1rem
+    @include toRem('font-size', 24px);    // Expected: 1.5rem
+    @include toRem('font-size', 32px);    // Expected: 2rem
 }
 
 // Lets test RTL support