Add Apple Podcasts icon (#784)

* add Apple Podcasts logo

* add Apple Podcasts reference image

* update reference index with Apple Podcast images

* updates README (via python script)

* fix: adds required attribute in stop element

* update README.md

Rerun python script to update README.md after
correcting Apple Podcasts svg.

images/svg/apple_podcasts.svg

@@ -0,0 +1,6 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+aria-label="Apple Podcasts" role="img"
+viewBox="0 0 512 512"><path
+d="m0 0H512V512H0"
+fill="url(#a)"/><linearGradient id="a" x2="0" y2="1"><stop offset="0" stop-color="#d56efc"/><stop offset="1" stop-color="#832bc1"/></linearGradient>
+<path d="M255.9 188.7a37 37 0 110 74 37 37 0 010-74ZM199.2 324.6a2 2 0 01-3.2 2 106.3 106.3 0 11119.86-.1 2 2 0 01-3.2-1.9l-.66-18.6c.7-1.5 1.5-3.4 3-4.7a86 86 0 10-118 .1 6.4 6.4 0 012 4.6ZM205.8 386.2c-.9333.7667-1.8667 1.5333-2.8 2.3a159 159 0 11105.2.1c-1.5.5-3-.7-2.9-2.3l2.3-16.3c1.0667-1.4 2.1333-2.8 3.2-4.2a138.6 138.6 0 10-110.5-.1c1.8.8 3 2.4 3.2 4.3ZM256 278c14 0 26 4.6 32.7 11.7 3.6 3.8 5.4 7.6 6 13a171 171 0 01-.7 34.2 823.5 823.5 0 01-6.3 51c-2 13.5-3.8 20.7-5.3 25.9-2.5 8.4-11.8 15.7-26.4 15.7s-23.9-7.4-26.4-15.7c-1.6-5.2-3.3-12.4-5.3-25.8a779.8 779.8 0 01-6.3-51.1 166.5 166.5 0 01-.8-34.2c.6-5.4 2.5-9.2 6-13a45 45 0 0132.8-11.7z" fill="#fff"/></svg>