chore: Remove travis; add cirrus CI.

Cirrus uses toktok-stack, so we'll still need a github workflow to test
the normal "go" build.

Author: iphydf

.cirrus.yml

@@ -0,0 +1,13 @@
+---
+cirrus-ci_task:
+  container:
+    image: toxchat/toktok-stack:0.0.11
+    cpu: 2
+    memory: 4G
+  configure_script:
+    - /src/workspace/tools/inject-repo go-toxcore-c
+  test_all_script:
+    - bazel test -k
+        --remote_http_cache=http://$CIRRUS_HTTP_CACHE_HOST
+        --config=release
+        //go-toxcore-c/...

.github/settings.yml

@@ -1,5 +1,5 @@
 ---
-_extends: template
+_extends: .github
 
 repository:
   name: go-toxcore-c
@@ -12,8 +12,5 @@ branches:
     protection:
       required_status_checks:
         contexts:
-          - Codacy/PR Quality Review
-          - Travis CI - Pull Request
-          - WIP
+          - Codacy Static Code Analysis
           - code-review/reviewable
-          - license/cla