bot: Update to Mercurial 6.3.1

Author: marco-c

bot/ci/bootstrap.sh

@@ -1,6 +1,6 @@
 #!/bin/bash -ex
 GRCOV_VERSION="v0.7.1"
-MERCURIAL_VERSION="5.6.1"
+MERCURIAL_VERSION="6.3.1"
 VERSION_CONTROL_TOOLS_REV="388ea44236d7"
 
 apt-get update

bot/tests/test__system.py

@@ -13,7 +13,7 @@ def test_mercurial():
 
     # Check mercurial version
     output = run_check(["hg", "version", "-T", "{ver}"])
-    assert output.decode("utf-8").startswith("5.6.1")
+    assert output.decode("utf-8").startswith("6.3.1")
 
     # Check needed extensions
     output = run_check(["hg", "version", "-T", "{extensions}"])