fix: fix nil sheet model append nil pointer reference. #9

	# This workflow will build a golang project
	# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-go

	name: Go

	on:
	push:
	branches: [ "master" ]
	pull_request:
	branches: [ "master" ]

	jobs:

	build:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3

	- name: Set up Go
	uses: actions/setup-go@v4
	with:
	go-version: '1.20'

	- name: Init
	run: go mod init github.com/varushsu/excelorm && go mod tidy

	- name: Test
	run: go test -v ./...

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