Because no versions of fakeredis match >1.6.1,<1.7.0 || >1.7.0,<1.7.1 || >1.7.1,<2.0.0
and fakeredis (1.6.1) depends on redis (<3.6.0), fakeredis (>=1.6.1,<1.7.0 || >1.7.0,<1.7.1 || >1.7.1,<2.0.0) requires redis (<3.6.0).
And because fakeredis (1.7.0) depends on redis (<4.1.0)
and fakeredis (1.7.1) depends on redis (<4.2.0), fakeredis (>=1.6.1,<2.0.0) requires redis (<4.2.0).
Because no versions of fastapi-mail match >1.0.8,<2.0.0
and fastapi-mail (1.0.8) depends on fakeredis (>=1.6.1,<2.0.0), fastapi-mail (>=1.0.8,<2.0.0) requires fakeredis (>=1.6.1,<2.0.0).
Thus, fastapi-mail (>=1.0.8,<2.0.0) requires redis (<4.2.0).
So, because ** depends on both redis (^4.2.2) and fastapi-mail (^1.0.8), version solving failed.
SolverProblemError
Because no versions of fakeredis match >1.6.1,<1.7.0 || >1.7.0,<1.7.1 || >1.7.1,<2.0.0 and fakeredis (1.6.1) depends on redis (<3.6.0), fakeredis (>=1.6.1,<1.7.0 || >1.7.0,<1.7.1 || >1.7.1,<2.0.0) requires redis (<3.6.0). And because fakeredis (1.7.0) depends on redis (<4.1.0) and fakeredis (1.7.1) depends on redis (<4.2.0), fakeredis (>=1.6.1,<2.0.0) requires redis (<4.2.0). Because no versions of fastapi-mail match >1.0.8,<2.0.0 and fastapi-mail (1.0.8) depends on fakeredis (>=1.6.1,<2.0.0), fastapi-mail (>=1.0.8,<2.0.0) requires fakeredis (>=1.6.1,<2.0.0). Thus, fastapi-mail (>=1.0.8,<2.0.0) requires redis (<4.2.0). So, because ** depends on both redis (^4.2.2) and fastapi-mail (^1.0.8), version solving failed.
fakeredis is not a dev dependency?