Update go version to satisfy vet.

Author: panmari

.github/workflows/go.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: [ '1.15', '>=1.5 <2']
+        go: [ '1.21', '>=1.21 <2']
     steps:
     - uses: actions/checkout@v4
 

go.mod

@@ -1,6 +1,6 @@
 module github.com/panmari/cuckoofilter
 
-go 1.15
+go 1.21
 
 require (
 	github.com/dgryski/go-metro v0.0.0-20200812162917-85c65e2d0165