[chore] Update to yarn 4 (#90)

Update to yarn 4 and use `masto-fe-standalone-woodpecker-build` container for builds.

Reviewed-on: https://codeberg.org/superseriousbusiness/masto-fe-standalone/pulls/90
Co-authored-by: tobi <tobi.smethurst@protonmail.com>
Co-committed-by: tobi <tobi.smethurst@protonmail.com>

.gitignore

@@ -55,6 +55,9 @@ npm-debug.log
 yarn-error.log
 yarn-debug.log
 
+# Ignore yarn state file
+.yarn/install-state.gz
+
 # Ignore vagrant log files
 *-cloudimg-console.log