Bump github.com/gorilla/mux from 1.8.0 to 1.8.1 #38

Job	Run time
Build for Windows (windows, amd64)	3m 26s
Build for Linux (linux, amd64)	3m 55s
Unit tests	2m 42s
Build for Linux (linux, 386)	1m 45s
Linting	2m 12s
WASM build test	0s
Initial tests passed	4s
Upgrade tests	7m 5s
Sytest (SQLite native)	4m 54s
Sytest (SQLite Cgo)	5m 56s
Integration tests	5m 22s
Complement (SQLite native)	5m 23s
Sytest (PostgreSQL)	7m 5s
Upgrade tests from HEAD-2	7m 39s
Complement (SQLite Cgo)	4m 32s
Complement (PostgreSQL)	8m 54s
Integration tests passed	2s
Update Docker images	0s
	1h 10m 56s

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