feat: Add `git-pull-request` icon

icons/git-pull-request.svg

+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <circle cx="18" cy="18" r="3" />
+  <circle cx="6" cy="6" r="3" />
+  <path d="M13 6h3a2 2 0 0 1 2 2v7" />
+  <line x1="6" y1="9" x2="6" y2="21" />
+</svg>