Add testing support for Go 1.21 (#4463)

* Add testing support for Go 1.21

* Add PR number in changelog

.github/workflows/benchmark.yml

@@ -4,7 +4,7 @@ on:
     branches:
       - main
 env:
-  DEFAULT_GO_VERSION: "1.20"
+  DEFAULT_GO_VERSION: "1.21"
 jobs:
   benchmark:
     name: Benchmarks

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ env:
   # backwards compatibility with the previous two minor releases and we
   # explicitly test our code for these versions so keeping this at prior
   # versions does not add value.
-  DEFAULT_GO_VERSION: "1.20"
+  DEFAULT_GO_VERSION: "1.21"
 jobs:
   lint:
     runs-on: ubuntu-latest
@@ -99,7 +99,7 @@ jobs:
   compatibility-test:
     strategy:
       matrix:
-        go-version: ["1.20", 1.19]
+        go-version: ["1.21", "1.20", 1.19]
         os: [ubuntu-latest, macos-latest, windows-latest]
         # GitHub Actions does not support arm* architectures on default
         # runners. It is possible to accomplish this with a self-hosted runner

.github/workflows/dependabot.yml

@@ -13,7 +13,7 @@ jobs:
         ref: ${{ github.head_ref }}
     - uses: actions/setup-go@v4
       with:
-        go-version: '^1.20.0'
+        go-version: '^1.21.0'
     - uses: evantorrie/mott-the-tidier@v1-beta
       id: modtidy
       with: