Bump version of pion/sdp

Update our dependency on pion/sdp from v2 to v3, to match pion/webrtc
v3. This requires some changes in how we parse out addresses from ice
candidates. This will ease tor browser builds of snowflake since we are
now only relying on one version of pion/sdp instead of two different
ones.
4 jobs for master in 6 minutes and 4 seconds (queued for 57 seconds)
Status Job ID Name Coverage
  Test
failed #9570
android

00:04:38

failed #9573
debian-testing

00:00:32

passed #9571
go-1.13

00:01:04

passed #9572
go-1.14

00:01:00

 
Name Stage Failure
failed
android Test
fmt
log
gomobile: go build -v -buildmode=c-shared -o=/tmp/gomobile-work-580230463/android/src/main/jniLibs/armeabi-v7a/libgojni.so ./gobind failed: exit status 2

Running after_script
Running after script...
$ echo "Download debug artifacts from https://gitlab.com/${CI_PROJECT_PATH}/-/jobs"
Download debug artifacts from https://gitlab.com/tpo/anti-censorship/pluggable-transports/snowflake/-/jobs
ERROR: Job failed: exit code 1
failed
debian-testing Test
   Last modification reported: Sun, 10 Jan 2021 21:57:19 +0000
E: Failed to fetch http://deb.debian.org/debian/pool/main/g/gcc-defaults/gcc_10.2.1-1_amd64.deb Bad header line Bad header data [IP: 199.232.98.132 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
Fetched 183 MB in 18s (10.1 MB/s)
Running after_script
Running after script...
$ echo "Download debug artifacts from https://gitlab.com/${CI_PROJECT_PATH}/-/jobs"
Download debug artifacts from https://gitlab.com/tpo/anti-censorship/pluggable-transports/snowflake/-/jobs
ERROR: Job failed: exit code 1