It's still a bad idea not to pin your dependencies even if you trust the author.
Say you want to check out some older version of the code for bisecting, and it doesn't even build anymore because it worked with some version of the dependencies that was the latest years ago, good luck figuring out what commit they were all on at the time.
It's trivial to just update your own project to point to the latest upstream SHA-1s and commit that, this is why git's own facility to do this (submodules) pins you at specific upstream commits.
Say you want to check out some older version of the code for bisecting, and it doesn't even build anymore because it worked with some version of the dependencies that was the latest years ago, good luck figuring out what commit they were all on at the time.
It's trivial to just update your own project to point to the latest upstream SHA-1s and commit that, this is why git's own facility to do this (submodules) pins you at specific upstream commits.