Use svg logo (#96)

This replaces the png logo by the new generated svg logo (see
insightsengineering/hex-stickers#39) to a slight
reduction on package size.

Related to
insightsengineering/nestdevs-tasks#93



![image](https://github.com/user-attachments/assets/220eda56-b5e5-4a30-b5a7-6d8cce871a6d)

README.Rmd

@@ -4,7 +4,7 @@ output: github_document
 <!-- markdownlint-disable-file -->
 <!-- README.md needs to be generated from README.Rmd. Please edit that file -->
 
-# ggplot2.utils <a href="https://insightsengineering.github.io/ggplot2.utils/"><img src="man/figures/logo.png" align="right" height="139" /></a>
+# ggplot2.utils <a href="https://insightsengineering.github.io/ggplot2.utils/"><img src="man/figures/logo.svg" align="right" height="139" /></a>
 
 ```{r, echo = FALSE}
 knitr::opts_chunk$set(

README.md

@@ -1,8 +1,9 @@
 
 <!-- markdownlint-disable-file -->
+
 <!-- README.md needs to be generated from README.Rmd. Please edit that file -->
 
-# ggplot2.utils <a href="https://insightsengineering.github.io/ggplot2.utils/"><img src="man/figures/logo.png" align="right" height="139" /></a>
+# ggplot2.utils <a href="https://insightsengineering.github.io/ggplot2.utils/"><img src="man/figures/logo.svg" align="right" height="139" /></a>
 
 <!-- badges: start -->