v3.3.2

Patch release that fixes several bugs and build issues:

• A recent change to CMake had the unintended consequence of
  installing headers and libraries from libdeflate when doing an
  internal build. This is now fixed.
• Fix custom namespaces
• Add thread control to exrmetrics tool
• Reintroduce single cache for successive scanline reads
• Allow empty filename when providing a custom stream
• Handle non-seekable stream in python module's InputFile object

This release fixes:

• OSS-fuzz 372524117 Null-dereference WRITE in Imf_3_4::ScanLineProcess::run_fill