Added call to calc to fix deprecations

[tip2tail]

Added an additional calc() to prevent these errors:

023-09-17 19:38:28 <w> Deprecation Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0.
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> Recommendation: math.div($connector-width, 2) or calc($connector-width / 2)
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> More info and automated migrator: https://sass-lang.com/d/slash-div
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> node_modules/treeflex/src/core/scss/treeflex.scss 36:25  @import
2023-09-17 19:38:28 <w> assets/css/tree.scss 1:9                                 root stylesheet
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> Deprecation Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0.
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> Recommendation: math.div($connector-width, 2) or calc($connector-width / 2)
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> More info and automated migrator: https://sass-lang.com/d/slash-div
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> node_modules/treeflex/src/core/scss/treeflex.scss 37:35  @import
2023-09-17 19:38:28 <w> assets/css/tree.scss 1:9                                 root stylesheet
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> Deprecation Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0.
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> Recommendation: math.div($connector-width, 2) or calc($connector-width / 2)
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> More info and automated migrator: https://sass-lang.com/d/slash-div
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> node_modules/treeflex/src/core/scss/treeflex.scss 44:26  @import
2023-09-17 19:38:28 <w> assets/css/tree.scss 1:9                                 root stylesheet
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> Deprecation Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0.
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> Recommendation: math.div($connector-width, 2) or calc($connector-width / 2)
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> More info and automated migrator: https://sass-lang.com/d/slash-div
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> node_modules/treeflex/src/core/scss/treeflex.scss 49:27  @import
2023-09-17 19:38:28 <w> assets/css/tree.scss 1:9                                 root stylesheet
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> Deprecation Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0.
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> Recommendation: math.div($node-gap, 2) or calc($node-gap / 2)
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> More info and automated migrator: https://sass-lang.com/d/slash-div
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> node_modules/treeflex/src/core/scss/treeflex.scss 65:15  @import
2023-09-17 19:38:28 <w> assets/css/tree.scss 1:9                                 root stylesheet
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> 8 repetitive deprecation warnings omitted.
2023-09-17 19:38:28 <w> 
2023-09-17 19:38:28 <w> null
2023-09-17 19:38:28