MAINT: Add optional HDF5 dependency

setup.cfg

@@ -39,3 +39,6 @@ per-file-ignores = __init__.py:F401
 [options.entry_points]
 console_scripts =
   caosdb-crawler = caoscrawler.crawl:main
+
+[options.extras_require]
+h5-crawler = h5py >= 3.8

src/caoscrawler/hdf5_converter.py

+#
+# This file is a part of the CaosDB Project.
+#
+# Copyright (C) 2023 IndiScale GmbH <info@indiscale.com>
+# Copyright (C) 2023 Florian Spreckelsen <f.spreckelsen@indiscale.com>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program. If not, see <https://www.gnu.org/licenses/>.
+#
+
+try:
+    import h5py
+except ModuleNotFoundError:
+    raise ModuleNotFoundError(
+        "Couldn't find module h5py. Did you install the crawler package with "
+        "its optional `h5-crawler` dependency?"
+    )