chore: update Go and Actions dependencies (#132)

## Summary
- Update Go dependencies: gitea SDK v0.22.1→v0.23.2, mcp-go v0.42.0→v0.44.0, zap v1.27.0→v1.27.1, go-version v1.7.0→v1.8.0, x/crypto v0.43.0→v0.48.0, x/sys v0.37.0→v0.41.0
- Update Actions: checkout v4→v6, setup-go v5→v6, build-push-action v5→v6, goreleaser-action v6→v7

## Test plan
- [x] `go test ./...` passes
- [x] `make build` succeeds

Reviewed-on: https://gitea.com/gitea/gitea-mcp/pulls/132
Co-authored-by: silverwind <me@silverwind.io>
Co-committed-by: silverwind <me@silverwind.io>

.gitea/workflows/release-nightly.yml

@@ -14,7 +14,7 @@ jobs:
       DOCKER_LATEST: nightly
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0 # all history for all branches and tags
 
@@ -37,7 +37,7 @@ jobs:
           echo REPO_VERSION=$(git describe --tags --always | sed 's/-/+/' | sed 's/^v//') >> $GITHUB_OUTPUT
 
       - name: Build and push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: ./Dockerfile

.gitea/workflows/release-tag.yml

@@ -10,15 +10,15 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version: stable
       - name: Run GoReleaser
-        uses: goreleaser/goreleaser-action@v6
+        uses: goreleaser/goreleaser-action@v7
         with:
           distribution: goreleaser
           # 'latest', 'nightly', or a semver
@@ -35,7 +35,7 @@ jobs:
       DOCKER_LATEST: latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0 # all history for all branches and tags
 
@@ -58,7 +58,7 @@ jobs:
           echo REPO_VERSION=${GITHUB_REF_NAME#v} >> $GITHUB_OUTPUT
 
       - name: Build and push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: ./Dockerfile

.gitea/workflows/test-pr.yml

@@ -7,8 +7,8 @@ jobs:
   check-and-test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-go@v5
+      - uses: actions/checkout@v6
+      - uses: actions/setup-go@v6
         with:
           go-version-file: 'go.mod'
       - name: lint