Set Rust MSRV to 1.60

It is the actual MSRV of the last released version

lib/Cargo.toml

@@ -12,6 +12,7 @@ description = """
 a SPARQL database and RDF toolkit
 """
 edition = "2021"
+rust-version = "1.60"
 
 [package.metadata.docs.rs]
 all-features = true

lib/oxrdf/Cargo.toml

@@ -11,6 +11,7 @@ description = """
 A library providing basic data structures related to RDF
 """
 edition = "2021"
+rust-version = "1.60"
 
 [features]
 default = []

lib/sparesults/Cargo.toml

@@ -11,6 +11,7 @@ description = """
 SPARQL query results formats parsers and serializers
 """
 edition = "2021"
+rust-version = "1.60"
 
 [features]
 default = []

lib/spargebra/Cargo.toml

@@ -11,6 +11,7 @@ description = """
 A SPARQL parser
 """
 edition = "2021"
+rust-version = "1.60"
 
 [features]
 default = []

oxrocksdb-sys/Cargo.toml

@@ -9,6 +9,7 @@ description = """
 Rust bindings for RocksDB for Oxigraph usage.
 """
 edition = "2021"
+rust-version = "1.60"
 build = "build.rs"
 links = "rocksdb"
 

server/Cargo.toml

@@ -10,6 +10,7 @@ description = """
 Oxigraph SPARQL HTTP server
 """
 edition = "2021"
+rust-version = "1.60"
 
 [dependencies]
 anyhow = "1"