Install git for showcase-unit-alternative-templates test cases

Author: lidizheng

.circleci/config.yml

@@ -439,7 +439,7 @@ jobs:
           name: Install system dependencies.
           command: |
             apt-get update
-            apt-get install -y curl pandoc unzip
+            apt-get install -y curl pandoc unzip git
       - run:
           name: Install protoc 3.12.1.
           command: |
@@ -463,7 +463,7 @@ jobs:
           name: Install system dependencies.
           command: |
             apt-get update
-            apt-get install -y curl pandoc unzip
+            apt-get install -y curl pandoc unzip git
       - run:
           name: Install protoc 3.12.1.
           command: |
@@ -487,7 +487,7 @@ jobs:
           name: Install system dependencies.
           command: |
             apt-get update
-            apt-get install -y curl pandoc unzip
+            apt-get install -y curl pandoc unzip git
       - run:
           name: Install protoc 3.12.1.
           command: |