ci: add go vet to lint step (#316)

- Adds `go vet` call to the lint step in GA workflow.
- Enforces a compatible `go-version` with the minimum in the matrix for
the `test` step.
- Fixes some minor `.yml` formatting

Fixes #281

---

There's some discussion in #281 about adding
[staticcheck](https://staticcheck.dev/docs/) as well but when I ran it,
it found some hits (see below) that are presumably not severe, and I
wouldn't want to block deployments before getting some feedback from
maintainers.

```
internal/jsonrpc2/conn.go:695:4: this value of writeErr is never used (SA4006)
internal/jsonrpc2/conn.go:697:5: this value of err is never used (SA4006)
internal/jsonrpc2/conn.go:700:4: this value of err is never used (SA4006)
mcp/mcp_test.go:501:2: var resource3 is unused (U1000)
mcp/mcp_test.go:509:5: var embeddedResources is unused (U1000)
mcp/mcp_test.go:513:6: func handleEmbeddedResource is unused (U1000)
mcp/streamable.go:124:3: unnecessary assignment to the blank identifier (S1005)
mcp/streamable.go:291:2: field lastStreamID is unused (U1000)
mcp/streamable.go:293:2: field opts is unused (U1000)
mcp/streamable_test.go:542:29: argument ctx is overwritten before first use (SA4009)
```

.github/workflows/test.yml

@@ -3,7 +3,7 @@ on:
   # Manual trigger
   workflow_dispatch:
   push:
-    branches: main
+    branches: [main]
   pull_request:
 
 permissions:
@@ -13,43 +13,47 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-    - name: Check out code
-      uses: actions/checkout@v4
-    - name: Set up Go
-      uses: actions/setup-go@v5
-    - name: Check formatting
-      run: |
-        unformatted=$(gofmt -l .)
-        if [ -n "$unformatted" ]; then
-          echo "The following files are not properly formatted:"
-          echo "$unformatted"
-          exit 1
-        fi
-        echo "All Go files are properly formatted"
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "^1.23"
+      - name: Check formatting
+        run: |
+          unformatted=$(gofmt -l .)
+          if [ -n "$unformatted" ]; then
+            echo "The following files are not properly formatted:"
+            echo "$unformatted"
+            exit 1
+          fi
+          echo "All Go files are properly formatted"
+      - name: Run Go vet
+        run: go vet ./...
 
   test:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: [ '1.23', '1.24', '1.25.0-rc.3' ]
+        go: ["1.23", "1.24", "1.25.0-rc.3"]
     steps:
-    - name: Check out code
-      uses: actions/checkout@v4
-    - name: Set up Go
-      uses: actions/setup-go@v5
-      with:
-        go-version: ${{ matrix.go }}
-    - name: Test
-      run: go test -v ./...
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: ${{ matrix.go }}
+      - name: Test
+        run: go test -v ./...
 
   race-test:
     runs-on: ubuntu-latest
     steps:
-    - name: Check out code
-      uses: actions/checkout@v4
-    - name: Set up Go
-      uses: actions/setup-go@v5
-      with:
-        go-version: '1.24'
-    - name: Test with -race
-      run: go test -v -race ./...
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "1.24"
+      - name: Test with -race
+        run: go test -v -race ./...