Fix CI issues related to Python upgrade (#33)

## What is the goal of this PR?

Recent upgrade to Python 3 broke our CI.

## What are the changes implemented in this PR?

- Use updated imports from `@rules_python`

Author: vmax

WORKSPACE

@@ -51,10 +51,13 @@ checkstyle_dependencies()
 load("@graknlabs_build_tools//bazel:dependencies.bzl", "bazel_rules_python")
 bazel_rules_python()
 
-load("@io_bazel_rules_python//python:pip.bzl", "pip_repositories", "pip_import")
+load("@rules_python//python:repositories.bzl", "py_repositories")
+py_repositories()
+
+load("@rules_python//python:pip.bzl", "pip_repositories", "pip3_import")
 pip_repositories()
 
-pip_import(
+pip3_import(
     name = "graknlabs_build_tools_ci_pip",
     requirements = "@graknlabs_build_tools//ci:requirements.txt",
 )
@@ -64,7 +67,7 @@ graknlabs_build_tools_ci_pip_install = "pip_install")
 graknlabs_build_tools_ci_pip_install()
 
 
-pip_import(
+pip3_import(
     name = "graknlabs_bazel_distribution_pip",
     requirements = "@graknlabs_bazel_distribution//pip:requirements.txt",
 )