feat: drop Ubuntu Bionic support

Fixes #2035

analyzer/tests/pipeline/analyze_replaygain_test.py

@@ -1,4 +1,3 @@
-import distro
 import pytest
 
 from libretime_analyzer.pipeline.analyze_replaygain import analyze_replaygain
@@ -13,10 +12,5 @@ from ..fixtures import FILES
 def test_analyze_replaygain(filepath, replaygain):
     tolerance = 0.8
 
-    # On bionic, replaygain is a bit higher for loud mp3 files.
-    # This huge tolerance makes the test pass, with values devianting from ~-17 to ~-13
-    if distro.codename() == "bionic" and str(filepath).endswith("+12.mp3"):
-        tolerance = 5
-
     metadata = analyze_replaygain(filepath, {})
     assert metadata["replay_gain"] == pytest.approx(replaygain, abs=tolerance)