Update strum requirement from 0.25 to 0.26

---
updated-dependencies:
- dependency-name: strum
  dependency-type: direct:production
...

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

Cargo.toml

@@ -55,7 +55,7 @@ smallvec = "1.6.1"
 cast = { version = "0.3", features = ["std"] }
 arrow = { version = "51", default-features = false, features = ["prettyprint", "ffi"] }
 rust_decimal = "1.14"
-strum = { version = "0.25", features = ["derive"] }
+strum = { version = "0.26", features = ["derive"] }
 r2d2 = { version = "0.8.9", optional = true }
 calamine = { version = "0.22.0", optional = true }
 num = { version = "0.4", optional = true, default-features = false, features = ["std"] }