Bump sympy from 1.6.2 to 1.7.1

Bumps [sympy](https://github.com/sympy/sympy) from 1.6.2 to 1.7.1.
- [Release notes](https://github.com/sympy/sympy/releases)
- [Commits](sympy/sympy@sympy-1.6.2...sympy-1.7.1)

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

requirements.txt

@@ -6,5 +6,5 @@ mistune==2.0.0a6  # for DictFile reading
 pillow==8.0.1
 pyglossary==4.0.10
 requests==2.25.1
-sympy==1.6.2
+sympy==1.7.1
 wikitextparser==0.47.0