ci(lint): refactor code for clarity and linting compliance (#289)

- Removed `deadcode`, `structcheck`, and `varcheck` linters from `.golangci.yml`
- Fixed a typo in a comment in `daemon.go`
- Renamed `defaultActionsUrl` to `defaultActionsURL` in `exec.go`
- Removed unnecessary else clause in `exec.go` and `runner.go`
- Simplified variable initialization in `exec.go`
- Changed function name from `getHttpClient` to `getHTTPClient` in `http.go`
- Removed unnecessary else clause in `labels_test.go`

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/289
Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Co-committed-by: Bo-Yi Wu <appleboy.tw@gmail.com>

internal/pkg/labels/labels_test.go

@@ -55,9 +55,8 @@ func TestParse(t *testing.T) {
 			if tt.wantErr {
 				require.Error(t, err)
 				return
-			} else {
-				require.NoError(t, err)
 			}
+			require.NoError(t, err)
 			assert.DeepEqual(t, got, tt.want)
 		})
 	}