Fixing `pijul git` with the new Sanakirja

Dependencies

• [2] IIV3EL2X Cleanup, formatting, and fixing the Git feature
• [3] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).
• [4] JL4WKA5P Implement the Sanakirja concurrency model in a cross-process way

Change contents

• replacement in pijul/src/commands/git.rs at line 57
  [3.138584]→[2.253:326](∅→∅)
  − let mut env_git = ::sanakirja::Env::new(&path_git, 1 << 15, 2)?;
  [3.138584]

  [3.138654]
  + let mut env_git = ::sanakirja::Env::new(&path_git.join("db"), 1 << 15, 2)?;