🐛 Replace deprecated convert command with magick

From https://imagemagick.org/script/porting.php#:~:text=Command%20Changes:

 "Porting to ImageMagick Version 7

  ...

  Command Changes

  Here are a list of changes to the ImageMagick commands:

  magick - The "magick" command is the new primary command of
           the Shell API, replacing the old "convert" command."

src/shell/bash_functions

@@ -229,10 +229,10 @@ rename-media-files() (
 
 resize-image() {
 
-    # Check if ImageMagick's convert command-line tool is installed.
+    # Check if ImageMagick's magick command-line tool is installed.
 
-    if ! command -v "convert" &> /dev/null; then
-        printf "ImageMagick's 'convert' command-line tool is not installed!"
+    if ! command -v "magick" &> /dev/null; then
+        printf "ImageMagick's 'magick' command-line tool is not installed!"
         exit
     fi
 
@@ -242,7 +242,7 @@ resize-image() {
     declare fileName="$(basename "$1")"
     declare geometry="${2:-50%}"
 
-    convert \
+    magick \
         "$1" \
         -colorspace RGB \
         +sigmoidal-contrast 11.6933 \