updating operator-sdk to 1.28.0 (#448)

Issue #, if available:
N/A
Description of changes:
Updating to use 1.28.0 of operator-sdk

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Author: acornett21

scripts/install-operator-sdk.sh

@@ -16,7 +16,7 @@ SCRIPTS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 ROOT_DIR="$SCRIPTS_DIR/.."
 DEFAULT_OPERATOR_SDK_BIN_PATH="$ROOT_DIR/../code-generator/bin"
 OPERATOR_SDK_BIN_PATH=${OPERATOR_SDK_BIN_PATH:-$DEFAULT_OPERATOR_SDK_BIN_PATH}
-DEFAULT_OPERATOR_SDK_VERSION="1.19.1"
+DEFAULT_OPERATOR_SDK_VERSION="1.28.0"
 
 source "${SCRIPTS_DIR}/lib/common.sh"