Bump go version in tests (so Dendrite unit tests can pass) (#413)

Signed-off-by: `Sam Wedgwood <[email protected]>`

Author: swedgwood

.github/workflows/tests.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: 1.18
+          go-version: 1.21
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v3
 
@@ -33,7 +33,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        go: ["1.18", "1.19"]
+        go: ["1.20", "1.21"]
     steps:
       - uses: actions/checkout@v3
       - name: Setup go
@@ -80,7 +80,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        go: ["1.18", "1.19"]
+        go: ["1.20", "1.21"]
     steps:
       - uses: actions/checkout@v3
         with: