Add a flag var to check git is installed or not

Signed-off-by: Wonyeong Choi <ciwnyg0815@gmail.com>

scripts/get-helm-3

@@ -29,6 +29,7 @@ HAS_CURL="$(type "curl" &> /dev/null && echo true || echo false)"
 HAS_WGET="$(type "wget" &> /dev/null && echo true || echo false)"
 HAS_OPENSSL="$(type "openssl" &> /dev/null && echo true || echo false)"
 HAS_GPG="$(type "gpg" &> /dev/null && echo true || echo false)"
+HAS_GIT="$(type "git" &> /dev/null && echo true || echo false)"
 
 # initArch discovers the architecture for this system.
 initArch() {
@@ -97,6 +98,11 @@ verifySupported() {
       exit 1
     fi
   fi
+
+  if [ "${HAS_GIT}" != "true" ]; then
+    echo "Git is required for plugin install"
+    exit 1
+  fi
 }
 
 # checkDesiredVersion checks if the desired version is available.