Use agent 0.2.7. (#2172)

diff --git a/buildkite/bazelci.py b/buildkite/bazelci.py
index 4606a64..808c056 100755
--- a/buildkite/bazelci.py
+++ b/buildkite/bazelci.py
@@ -1628,7 +1628,7 @@
     repo = "bazelbuild/continuous-integration"
     if THIS_IS_TESTING and "BAZELCI_AGENT_REPO" in os.environ:
         repo = os.environ["BAZELCI_AGENT_REPO"]
-    version = "0.2.6"
+    version = "0.2.7"
     if THIS_IS_TESTING and "BAZELCI_AGENT_VERSION" in os.environ:
         version = os.environ["BAZELCI_AGENT_VERSION"]
     postfix = ""