Provide Python 3 matplotlib

Once I get around to making numpy/scipy imported for Python 3, I'll
probably upgrade everything to Python 3 and drop Python 2 support from
the codebase, but I don't feel like doing that quite yet.

Change-Id: I164c8fbb3ce922a83b56e46f5cc432004c3a989c
diff --git a/frc971/analysis/BUILD b/frc971/analysis/BUILD
index b526712..87a64ee 100644
--- a/frc971/analysis/BUILD
+++ b/frc971/analysis/BUILD
@@ -12,7 +12,7 @@
     restricted_to = ["//tools:k8"],
     deps = [
         ":python_init",
-        "@matplotlib",
+        "@matplotlib_repo//:matplotlib2.7",
     ],
 )