ci: exclude release compare URLs from link checker (#76)

Release-please generates compare URLs like
patchloom-v0.0.0...patchloom-v0.0.1 in CHANGELOG.md. These tags
do not exist until the release PR merges, so lychee reports 404.
Exclude the compare URL prefix alongside the store exclusions.
Remove all three exclusions after the first successful release.

Signed-off-by: Sebastien Tardif <sebtardif@ncf.ca>

Author: SebTardif

lychee.toml

@@ -10,8 +10,10 @@ timeout = 30
 # Max concurrent requests
 max_concurrency = 4
 
-# Exclude store URLs that return 404 until first publish
+# Exclude URLs that return 404 until first publish.
+# Remove these exclusions after the first successful release.
 exclude = [
   "https://marketplace.visualstudio.com/items\\?itemName=patchloom\\.patchloom",
   "https://open-vsx.org/extension/patchloom/patchloom",
+  "https://github.com/patchloom/patchloom-vscode/compare/patchloom-v",
 ]