Fix SVG validation errors on bluesky logo

Turns out hand-editing SVGs doesn't always work out :D

static/assets/bluesky.svg

@@ -1,11 +1,18 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <!-- This icon originated from https://commons.wikimedia.org/wiki/File:Bluesky_Logo.svg -->
-<?xml version="1.0" encoding="UTF-8"?><svg
-   width="27px"
-   height="24px"
-   xmlns="http://www.w3.org/2000/svg">
+
+<svg
+   width="27"
+   height="24"
+   viewBox="0 0 27 24"
+   version="1.1"
+   id="svg1"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <defs
+     id="defs1" />
   <path
      d="m 5.8526068,1.615495 c 3.095485,2.346093 6.4250312,7.102992 7.6474722,9.65582 1.222534,-2.55264 4.551894,-7.309774 7.647473,-9.65582 C 23.38109,-0.07735119 27,-1.3871796 27,2.780764 c 0,0.832395 -0.47273,6.99255 -0.74999,7.992627 -0.963755,3.47696 -4.475643,4.363776 -7.599525,3.827034 5.460485,0.93823 6.849581,4.045988 3.849666,7.153747 -5.697433,5.902241 -8.188866,-1.480894 -8.827552,-3.372723 -0.117031,-0.346817 -0.171794,-0.509061 -0.172599,-0.3711 -8.1e-4,-0.137966 -0.05557,0.02428 -0.172599,0.3711 -0.638406,1.891829 -3.129794,9.275152 -8.8275522,3.372723 -2.999961,-3.107759 -1.610912,-6.215705 3.849666,-7.153747 -3.123975,0.536742 -6.63591,-0.350079 -7.59952495,-3.827034 C 0.47272085,9.77322 -1.5106201e-7,3.613065 -1.5106201e-7,2.780764 -1.5106201e-7,-1.3871796 3.6190028,-0.07735119 5.8524478,1.615495 Z"
      fill="currentColor"
-     viewBox="0 0 27 24"
-     />
+     id="path1" />
 </svg>