fix: resolve CI linting and code quality issues

- Remove unused imports across all generator files
- Remove unused variables (spec, url_params, query_params, test_name)
- Fix f-strings without placeholders in auth.py and go.py
- Fix duplicate BASIC auth handling with wrong indentation
- Add missing pytest fixtures (sample_openapi_spec, temp_spec_file, temp_json_spec_file)
- Add missing TemplateRenderError import to generator files

api_testgen/generators/go.py

@@ -6,8 +6,8 @@ from typing import Any, Dict, List, Optional
 
 from jinja2 import Environment, FileSystemLoader, TemplateSyntaxError, UndefinedError
 
-from ..core import SpecParser, AuthConfig
-from ..core.exceptions import GeneratorError, TemplateRenderError
+from ..core import SpecParser
+from ..core.exceptions import TemplateRenderError
 
 
 class GoGenerator:
@@ -132,7 +132,6 @@ class GoGenerator:
         """
         test_name = self._generate_test_name(endpoint)
         params = self._generate_params(endpoint)
-        url_params = self._generate_url_params(endpoint)
 
         test_code = f'''
 func Test{test_name}(t *testing.T) {{
@@ -201,11 +200,11 @@ func Test{test_name}(t *testing.T) {{
 
             if param["in"] == "path":
                 params.append(f'{param_name} := "test_{param_name}"')
-                params.append(f'url = strings.Replace(url, "{{'+param_name+'}}", {param_name}, 1)')
+                params.append('url = strings.Replace(url, "' + '{' + param_name + '}' + '", ' + param_name + ', 1)')
 
             elif param["in"] == "query":
                 params.append(f'q := url.Values{{{param_name}: []string{{"test"}}}}')
-                params.append(f'url += "?" + q.Encode()')
+                params.append('url += "?" + q.Encode()')
 
         return "\n    ".join(params) if params else ""
 
@@ -219,11 +218,10 @@ func Test{test_name}(t *testing.T) {{
             String containing URL parameter handling.
         """
         path_params = [p for p in endpoint.get("parameters", []) if p["in"] == "path"]
-        query_params = [p for p in endpoint.get("parameters", []) if p["in"] == "query"]
 
         parts = []
 
         for param in path_params:
-            parts.append(f'strings.Replace(url, "{{'+param['name']+'}}", "test_' + param['name'] + '", 1)')
+            parts.append('strings.Replace(url, "' + '{' + param['name'] + '}' + '", "test_' + param['name'] + '", 1)')
 
         return ""