Add support for BioCAM files recorded with BrainWave 6 (#458)

* BRW6

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: b-grimaud

src/probeinterface/io.py

@@ -567,7 +567,10 @@ def read_3brain(file: str | Path, mea_pitch: float = None, electrode_width: floa
         num_channels = None
         for key in rf:
             if key.startswith("Well_"):
-                num_channels = len(rf[key]["StoredChIdxs"])
+                if "ExperimentSettings" in rf:  # BRW5
+                    num_channels = len(rf[key]["StoredChIdxs"])
+                elif "ExperimentInfo" in rf:  # BRW6
+                    num_channels = max(rf[key]["NoisePlateElIdxs"]) + 1
                 break
         assert num_channels is not None, "No Well found in the file"