docker: Upload filesize

[mtettke123]

Please confirm you have done the following before posting your bug report:

• I have enabled debug mode (How to enable in docker?)
• I have read checked the Common Issues page

Describe the bug
When using the dockler image, upload filesize is not 8 MB

To Reproduce
Steps to reproduce the behavior:

1. Go to any asset,
2. Click on 'files'
3. click on upload
4. chosse a file with a size > 5 MB (?) but < 8 MB
5. Enjoy the error message

Expected behavior
The file should be uploaded, no error should be displayed

Screenshots

Server (please complete the following information):

• Snipe-IT Version: Version v5.1.5 - build 6055 (master)
• OS: Debian 10 with docker

Desktop (please complete the following information):

• OS: Win10
• Browser: Firefox
• Version: 88.0.1

Error Messages

• WITH DEBUG TURNED ON, if you're getting an error in your browser, include that error
• If a stacktrace is provided in the error, include that too.
• Any errors that appear in your browser's error console.
• Confirm whether the error is reproducible on the demo: https://snipeitapp.com/demo.
  No, it works in the demo:

• Include any additional information you can find in storage/logs and your webserver's logs. does not exist in docker
• Include the output from php -m (this should display what modules you have enabled.) (docker)

Additional context

• Is this a fresh install or an upgrade? Fresh
• What OS and web server you're running Snipe-IT on (docker)
• What method you used to install Snipe-IT (install.sh, manual installation, docker, etc) docker
• Include what you've done so far in the installation, and if you got any error messages along the way. no errors but this one
• Indicate whether or not you've manually edited any data directly in the database: no

[welcome]

👋 Thanks for opening your first issue here! If you're reporting a 🐞 bug, please make sure you include steps to reproduce it. We get a lot of issues on this repo, so please be patient and we will get back to you as soon as we can.

[mtettke123]

added: here is the reason. So simple.
#6251

PLEASE update the docker image!

[snipe]

I'm happy to take a PR to resolve this.

[snipe]

Closing as duplicate of #6251