Update releases displayed in plugins matrix

Change-Id: I028ac206878799bdb1d4853238e34f0a0f2a27c4
diff --git a/tools/plugins.py b/tools/plugins.py
index 5f4477f..09f0c0b 100644
--- a/tools/plugins.py
+++ b/tools/plugins.py
@@ -20,7 +20,7 @@
 
 
 BRANCHES = ["master"] + [
-    f"stable-{version}" for version in ["3.6", "3.5", "3.4"]
+    f"stable-{version}" for version in ["3.8", "3.7", "3.6"]
 ]
 CI = "https://gerrit-ci.gerritforge.com"
 GERRIT = "https://gerrit-review.googlesource.com"