test: webtransport with certhash (#276)

This PR adds tests for real-world example of webtransport 
addr announced by Kubo 0.16.0-rc1 (with two certhashes).

test/index.spec.ts

@@ -347,7 +347,7 @@ describe('variants', () => {
     expect(addr.toString()).to.equal(str)
   })
 
-  it('webtransport', () => {
+  it('ip6 webtransport', () => {
     const str = '/ip6/2001:8a0:7ac5:4201:3ac9:86ff:fe31:7095/udp/4001/quic/webtransport'
     const addr = multiaddr(str)
     expect(addr).to.have.property('bytes')
@@ -361,6 +361,13 @@ describe('variants', () => {
     expect(addr.toString()).to.equal(str)
   })
 
+  it('webtransport with certhash', () => {
+    const str = '/ip4/1.2.3.4/udp/4001/quic/webtransport/certhash/uEiAkH5a4DPGKUuOBjYw0CgwjvcJCJMD2K_1aluKR_tpevQ/certhash/uEiAfbgiymPP2_nX7Dgir8B4QkksjHp2lVuJZz0F79Be9JA/p2p/12D3KooWBdmLJjhpgJ9KZgLM3f894ff9xyBfPvPjFNn7MKJpyrC2'
+    const addr = multiaddr(str)
+    expect(addr).to.have.property('bytes')
+    expect(addr.toString()).to.equal(str)
+  })
+
   it('unix', () => {
     const str = '/unix/a/b/c/d/e'
     const addr = multiaddr(str)