Update Flatpak install instructions

7 jobs for v0.11.9 in 25 minutes and 15 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Test
passed #756876482
lint

00:02:15

passed #756876483
test

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40.0%
 
  Build
passed #756876484
build

00:01:57

passed #756876485
build_flatpak

00:17:26

 
  Deploy
passed #756876486
deploy_pypi

00:01:16

 
  Verify
passed #756876487
verify_deploy

00:02:14

 
  Release
passed #756876488
publish_release

00:02:03