Add git.Blob fuzz target

Based on the `test_blob.py` unit test.

Author: DaveLak

Diff for: fuzzing/dictionaries/fuzz_blob.dict

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+"\\377\\377\\377\\377\\377\\377\\377\\377" 

Diff for: fuzzing/fuzz-targets/fuzz_blob.py

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+import atheris
+import sys
+import os
+import tempfile
+
+if getattr(sys, "frozen", False) and hasattr(sys, "_MEIPASS"):
+    path_to_bundled_git_binary = os.path.abspath(os.path.join(os.path.dirname(__file__), "git"))
+    os.environ["GIT_PYTHON_GIT_EXECUTABLE"] = path_to_bundled_git_binary
+
+with atheris.instrument_imports():
+    import git
+
+
+def TestOneInput(data):
+    fdp = atheris.FuzzedDataProvider(data)
+
+    with tempfile.TemporaryDirectory() as temp_dir:
+        repo = git.Repo.init(path=temp_dir)
+        blob = git.Blob(
+            repo,
+            **{
+                "binsha": git.Blob.NULL_BIN_SHA,
+                "path": fdp.ConsumeUnicodeNoSurrogates(fdp.remaining_bytes()),
+            },
+        )
+
+        _ = blob.mime_type
+
+
+def main():
+    atheris.Setup(sys.argv, TestOneInput)
+    atheris.Fuzz()
+
+
+if __name__ == "__main__":
+    main()