Added Missing Include: ostream #1533

Job	Run time
test (ubuntu-latest, Release, -DCMAKE_CXX_COMPILER=clang++)	31s
test (ubuntu-latest, Debug, -DCMAKE_CXX_COMPILER=clang++)	22s
doc	6s
test (ubuntu-latest, Debug, -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_CXX_FLAGS="-fsanitize=address -f...	23s
test (ubuntu-latest, Debug, -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_CXX_FLAGS="-fsanitize=undefined ...	27s
test (ubuntu-latest, Release, true, -DCMAKE_CXX_COMPILER=g++-10)	34s
test (ubuntu-latest, Debug, true, -DCMAKE_CXX_COMPILER=g++-10)	32s
test (macos-latest, Release)	26s
test (macos-latest, Debug)	21s
test (windows-latest, Debug, -T ClangCL)	1m 35s
test (windows-latest, Release, -T ClangCL)	1m 50s
test (windows-latest, Debug)	1m 54s
test (windows-latest, Release)	2m 46s
	11m 47s

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