Calling a string from smart contract in go

Question

all I want to do is call a string from a smart contract I've written using go.

My smart contract is:

pragma solidity ^0.4.24;
contract String {
    string store = "abcdef";

    function getStore() public view returns (string) {
        return store;
    }

    function setStore(string _value) public {
        store = _value;
    }
}

My go code looks like this:

package main

import (
    "context"
    "log"

    "github.com/ethereum/go-ethereum"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/ethclient"
)

func main() {
    client, _ := ethclient.Dial("RPC_SERVER")
    defer client.Close()

    contractAddr := common.HexToAddress("0xe78250E6c91bac56C7F5326fe5dD5db7f4f7FaaD")
    callMsg := ethereum.CallMsg{
        To:   &contractAddr,
        Data: common.FromHex("0x8da5cb5b"),
    }

    res, err := client.CallContract(context.Background(), callMsg, nil)
    if err != nil {
        log.Fatalf("Error calling contract: %v", err)
    }
    log.Printf("version: %s", common.BytesToAddress(res).Hex())
}

I do understand that it is calling the owner address of this contract and that's the problem, I don't know how to call the string.