Re-order some CI steps

With GitHub's recent change to enforce stronger hash algorithms,
Circle CI was unable to clone the project repository.  By installing
our dependencies earlier in the workflow, we are able to ensure that
the AL2 git and ssh clients are used, which do support the newer
algorithms.

Details in this discussion on the Circle CI forums:
https://discuss.circleci.com/t/discussion-and-resolution-for-error-youre-using-an-rsa-key-with-sha-1-which-is-no-longer-allowed/42572

Author: Noah Meyerhans

.circleci/config.yml

@@ -9,12 +9,12 @@ jobs:
     docker:
       - image: public.ecr.aws/amazonlinux/amazonlinux:2
     steps:
-      - checkout
       - run:
           name: "Install dependencies"
           command: |
             yum -y install python-pip git
             pip install flake8
+      - checkout
       - run:
           name: "flake8"
           command: "git grep -l '^#!/usr/bin/env python' | xargs flake8 ebsnvme-id"
@@ -23,11 +23,11 @@ jobs:
     docker:
       - image: public.ecr.aws/amazonlinux/amazonlinux:2
     steps:
-      - checkout
       - run:
           name: "Install dependencies"
           command: |
-            yum -y install rpm-build python
+            yum -y install rpm-build python git
+      - checkout
       - run:
           name: "rpmbuild"
           command: "rpmbuild --define \"_sourcedir $PWD\" -bb amazon-ec2-utils.spec"