chore(ci): pin runner to ubuntu 20.04 (#319)

## Problem

Lint tests and CI tests were failing.

## Solution

Pin ristretto test runner to Ubuntu 20.04, and bump up linter
dependencies.

.github/workflows/ci-ristretto-lint.yml

@@ -13,15 +13,14 @@ jobs:
     name: lint
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: golang-lint
         env:
           # prevent OOM
           GOGC: 10
-        uses: golangci/golangci-lint-action@v2
+        uses: golangci/golangci-lint-action@v3
         with:
           # Required: the version of golangci-lint is required and must be specified without patch version: we always use the latest patch version.
-          version: v1.36
+          version: v1.48
           only-new-issues: true
           args: --timeout=10m
-          skip-go-installation: true

.github/workflows/ci-ristretto-tests.yml

@@ -10,14 +10,13 @@ on:
     - cron: "30 * * * *"
 jobs:
   ristretto-tests:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v3
       - name: Get Go Version
         run: |
           #!/bin/bash
-          DEFAULT_VERSION="1.17"
-          GOVERSION=$({ [ -f .go-version ] && cat .go-version; } || echo $DEFAULT_VERSION)
+          GOVERSION=$({ [ -f .go-version ] && cat .go-version; })
           echo "GOVERSION=$GOVERSION" >> $GITHUB_ENV
       - name: Setup Go
         uses: actions/setup-go@v3