.gitattributes: ensure t/oid-info/* has eol=lf

The new test_oid machinery in the test library requires reading
some information from t/oid-info/hash-info and t/oid-info/oid.
The shell logic that reads from these files is sensitive to CRLF
line endings, causing a failure when the test suite is run on a
Windows machine that converts LF to CRLF: the test suite fails
with a "bad hash algorithm" message, but does not record any
failed test cases. This caused CI builds to pass because they
fail only after reporting the failed test cases.

Exclude the files in this folder from this conversion.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>

Author: derrickstolee

.gitattributes

@@ -13,3 +13,4 @@
 /Documentation/gitk.txt conflict-marker-size=32
 /Documentation/user-manual.txt conflict-marker-size=32
 /t/t????-*.sh conflict-marker-size=32
+/t/oid-info/* eol=lf