Tests: Do not remove filename from boost filesystem path for corner

cases.

Co-authored-by: Kamil Śliwak <kamil.sliwak@codepoets.it>

test/libsolidity/syntaxTests/imports/boost_filesystem_bug.sol

@@ -0,0 +1,4 @@
+==== Source://// ====
+// This test used to throw due to a bug in boost::filesystem.
+// See https://github.com/boostorg/filesystem/issues/176
+import ".";

test/stopAfterParseTests.sh

@@ -70,5 +70,5 @@ while read -r file; do
 		echo "$file"
 		exit 1
 	fi
-done < <(find "${REPO_ROOT}/test" -iname "*.sol" -and -not -name "documentation.sol")
+done < <(find "${REPO_ROOT}/test" -iname "*.sol" -and -not -name "documentation.sol" -and -not -name "boost_filesystem_bug.sol")
 echo