fix(bitbucket): remove trailing comma in API calls (#2258)

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## What this PR does / why we need it:

Cherry-picked from #2257

Thanks @lieranderl for the contribution!

## Does this PR introduce a user-facing change?
<!--
If no, just write "no" in the block below.
If yes, please explain the change and update documentation and the
CHANGELOG.md file accordingly.
-->
```
yes, see changelog
```

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Fix Bitbucket PR lookup query to avoid a trailing comma in `fields`,
add a test, update changelog, and bump version.
> 
> - **Bitbucket Integration**:
> - Fix `GetPullRequestsByCommit` fields query construction in
`cloud/integrations/bitbucket/bitbucket.go` to join field names without
a trailing comma.
> - **Tests**:
> - Add `cloud/integrations/bitbucket/bitbucket_test.go` validating no
trailing comma in the `fields` parameter.
> - **Docs/Changelog**:
> - Update `CHANGELOG.md` under `Unreleased` with a fix note for the
Bitbucket integration.
> - **Versioning**:
>   - Bump `VERSION` to `0.15.2-dev`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
0df55c1. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: snakster

CHANGELOG.md

@@ -20,6 +20,12 @@ Given a version number `MAJOR.MINOR.PATCH`, we increment the:
 - Backward compatibility in versions `0.0.z` is **not guaranteed** when `z` is increased.
 - Backward compatibility in versions `0.y.z` is **not guaranteed** when `y` is increased.
 
+## Unreleased
+
+### Fixed
+
+- Fix invalid API query in Bitbucket integration.
+
 ## 0.15.1
 
 ### Added

VERSION

@@ -1 +1 @@
-0.15.1
+0.15.2-dev

cloud/integrations/bitbucket/bitbucket.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strings"
 	"time"
 
 	"github.com/terramate-io/terramate/errors"
@@ -178,13 +179,13 @@ func (c *Client) GetPullRequestsByCommit(ctx context.Context, commit string) (pr
 		"links",
 	}
 
-	fieldsQuery := ""
+	var fieldsQuery []string
 	for _, f := range fields {
-		fieldsQuery += fmt.Sprintf("values.%s,", f)
+		fieldsQuery = append(fieldsQuery, fmt.Sprintf("values.%s", f))
 	}
 
 	url := fmt.Sprintf("%s/repositories/%s/%s/commit/%s/pullrequests?fields=%s",
-		c.baseURL(), c.Workspace, c.RepoSlug, commit, fieldsQuery)
+		c.baseURL(), c.Workspace, c.RepoSlug, commit, strings.Join(fieldsQuery, ","))
 
 	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
 	if err != nil {

cloud/integrations/bitbucket/bitbucket_test.go

@@ -0,0 +1,50 @@
+// Copyright 2025 Terramate GmbH
+// SPDX-License-Identifier: MPL-2.0
+
+package bitbucket
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestClient_GetPullRequestsByCommit_TrailingComma(t *testing.T) {
+	// Setup a mock server that checks for the trailing comma
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Check that the URL path and query parameters are correct
+		if !strings.Contains(r.URL.Path, "/repositories/workspace/repo/commit/commit-hash/pullrequests") {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+
+		fields := r.URL.Query().Get("fields")
+		// Assert that 'fields' query parameter does NOT end with a comma
+		if strings.HasSuffix(fields, ",") {
+			w.WriteHeader(http.StatusBadRequest)
+			_, _ = w.Write([]byte("Trailing comma detected in fields parameter"))
+			return
+		}
+
+		// Return a valid empty response if the request is correct
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte(`{"values": []}`))
+	}))
+	defer server.Close()
+
+	client := Client{
+		BaseURL:   server.URL,
+		Workspace: "workspace",
+		RepoSlug:  "repo",
+		Token:     "token",
+	}
+
+	_, err := client.GetPullRequestsByCommit(context.Background(), "commit-hash")
+
+	// We expect NO error now
+	if err != nil {
+		t.Fatalf("Expected no error, but got: %v", err)
+	}
+}