Update ffsim requirement from ~=0.0.83 to ~=0.0.84 in /scripts/nb-tester

Updates the requirements on [ffsim](https://github.com/qiskit-community/ffsim) to permit the latest version.
- [Release notes](https://github.com/qiskit-community/ffsim/releases)
- [Commits](qiskit-community/ffsim@v0.0.83...v0.0.84)

---
updated-dependencies:
- dependency-name: ffsim
  dependency-version: 0.0.84
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

scripts/nb-tester/requirements.txt

@@ -21,5 +21,5 @@ pyscf~=2.14.0; sys.platform != 'win32'
 python-sat~=1.9.dev14
 plotly~=6.9.0
 gem-suite~=0.1.6
-ffsim~=0.0.83; sys.platform != 'win32'
+ffsim~=0.0.84; sys.platform != 'win32'
 sympy~=1.14.0